**6. Management of highly sensitized renal transplant candidates with anti-HLA antibodies**

**Number Technique Outcomes Complications**

Detection of Antibody-Mediated Rejection in Kidney Transplantation and the Management of Highly Sensitised…

• Wait-time pretransplant 144±89m, additional 5±6m (range

• Wait-time for DD pretransplant 95±46m, additional 4.2±4.5 postdesensitisation • AMR 29% (11DD/

• 2yGS 84%, PS 95% (LD 90%/100%, DD 80%/

• 2yCr - 143µmol/L

• 1y GS – 90% vs 98% (historical controls) • 5y GS – 69% vs 81% • Graft half-life 6.8y • 12% AMR

• 50% AMR and 54\$ TG in CDC-XM+ (vs 1% and

• DCGF 46% vs 0% at 2y

• AR 43% 1y (24% AMR)

• 42% ACR and 39% AMR (no difference with

0% controls)

• 1y DCGS 93% • 1y PS 95%

rituximab)

• 80% Cr <160 • 30% AR (cellular) <3m (Pre-Tx DSA <5000)

• 44% asymptomatic

117

• 11% infections, 8%

• 5% mortality (2.5%

CMV/BKV

infections)

• 10% PNF • 10% mortality (sepsis)

units • 30% sepsis • 21% CMV

• 70% transfusions ≥5

• Infection rates similar

• Not reported

• Infection risk with

• Not significant

rituximab • 7% CMV

UTI

http://dx.doi.org/10.5772/54735

2-18) postdesensitisation • 12mGS 94% • 12mPS 100% • 50% AR (30%AMR)

11LD)

91%)

• IVIg 2g/kg day 0 and 30 + rituximab 1g day

• IVIg 2g/kg day 1 and 30 + rituximab 1g

• Rituximab 375mg/m2 day -14 + 5PP with 0.1g/kg post-4PP + 2g/kg IVIg post-final PP • Induction basiliximab

• Alternate day PP (mean 4) + post-PP

IVIg + induction T cell

• Daily PP with post-PP 0.1g/kg IVIg ± splenectomy or rituximab (d-7) + rATG

• 3-5 PP with post-PP 0.1g/kg IVIg ± rituximab (1-2 doses 375mg/m2)

• 3x/week PP with 10g IVIg post-PP ± rituximab pre-transplant (375mg/m2)

0.1g/kg

depletion

induction

7 and 22 (5/16 CDC-XM+)

day 15

*Vo A et al* [72] • 10/11 LD and 6/9 DD

*Vo A et al* [62] • 76 (31 LD & 45 DD)

*Rogers N et al* [108]

*Haririan A et al*

[69]

*Gloor J et al* [106]

*Thielke J et al* [109]

*Magee C et al* [110]

with CDC-XM or FCMX+ (Note: 13/16 had persistently positive XM at time of transplant)

with T cells FCMX+ F/up 18m

• 10/13 LD with CDCXM+ and DSA+ successful(DSA up to 18,000 MFI)

• 41 LD with FCMX+ with 27 B/T cell+ (vs historical

controls)

controls

to XM-

• 119 LD +CM (52 CDC-XM+) vs 70

• 49/57 LD FCMX+ successfully desensitised

• 29 LD CDC-XM T or B-cell +

The complexity of transplantation has evolved over the years such that many transplanting cen‐ tres are performing ABO-incompatible transplants and desensitizing highly allo-sensitized transplant candidates to improve their transplant potential. There is an increasing number of transplant candidates who are allo-sensitised to HLA as a result of previous exposure to HLA an‐ tigens, typically following blood transfusion, prior transplantation and pregnancy. It is well known that the presence of high levels of pre-transplant DSA is associated with poorer graft out‐ comes, including the development of acute and chronic AMR resulting in late graft loss [26, 56]. Finding a compatible donor for potential transplant candidates with multiple anti-HLA antibod‐ ies is often difficult and these patients may remain on the deceased donor transplant wait-list for a much longer period compared to unsensitized transplant candidates. Paired kidney exchange program is a potential and proven option for highly sensitized patients who have a positive crossmatch with their potential live donors to receive a compatible cross-match negative donors [57]. With the greater understanding of HLA antigens and anti-HLA antibodies, innovative techni‐ ques have been established to allow transplantation across a 'positive CDC and/or flow cytomet‐ ric cross-match' barrier resulting from anti-HLA antibodies directed against the donor. Nevertheless, graft outcomes of highly sensitized transplant recipients are poorer compared to compatible transplant recipients, particularly a much greater risk of acute AMR (Table 4).


\*ANZDATA 2010 – graft failure secondary to AR 2%; #Stratified by donor type – death-censored graft survival at 1 and 2 years for LD 90% and 90%; for DD 82% and 80%. [Note: Of the total 374 recipients, only 51 [13.6%) were DD transplants].

Acute AMR is a strong predictor of inferior graft survival: 1] ^AMR vs no AMR – 1y GS 60% vs 89% (Lefaucheur et al); 2] θ AMR vs no AMR – development of transplant glomerulopathy 44% and 12% (Gloor et al).

Abbreviations: ANZDATA – Australia and New Zealand Dialysis and Transplant registry, AMR – antibody mediated rejection, DD – deceased donor, LD – live-donor.

**Table 4.** Incidence of antibody mediated rejection and graft survival following positive crossmatch kidney transplantation.

Detection of Antibody-Mediated Rejection in Kidney Transplantation and the Management of Highly Sensitised… http://dx.doi.org/10.5772/54735 117

**6. Management of highly sensitized renal transplant candidates with anti-**

The complexity of transplantation has evolved over the years such that many transplanting cen‐ tres are performing ABO-incompatible transplants and desensitizing highly allo-sensitized transplant candidates to improve their transplant potential. There is an increasing number of transplant candidates who are allo-sensitised to HLA as a result of previous exposure to HLA an‐ tigens, typically following blood transfusion, prior transplantation and pregnancy. It is well known that the presence of high levels of pre-transplant DSA is associated with poorer graft out‐ comes, including the development of acute and chronic AMR resulting in late graft loss [26, 56]. Finding a compatible donor for potential transplant candidates with multiple anti-HLA antibod‐ ies is often difficult and these patients may remain on the deceased donor transplant wait-list for a much longer period compared to unsensitized transplant candidates. Paired kidney exchange program is a potential and proven option for highly sensitized patients who have a positive crossmatch with their potential live donors to receive a compatible cross-match negative donors [57]. With the greater understanding of HLA antigens and anti-HLA antibodies, innovative techni‐ ques have been established to allow transplantation across a 'positive CDC and/or flow cytomet‐ ric cross-match' barrier resulting from anti-HLA antibodies directed against the donor. Nevertheless, graft outcomes of highly sensitized transplant recipients are poorer compared to compatible transplant recipients, particularly a much greater risk of acute AMR (Table 4).

**patients AMR incidence (%) 1-year graft survival**

[70] 51 32 93 81

<5% <5%

\*ANZDATA 2010 – graft failure secondary to AR 2%; #Stratified by donor type – death-censored graft survival at 1 and 2 years for LD 90% and 90%; for DD 82% and 80%. [Note: Of the total 374 recipients, only 51 [13.6%) were DD

Acute AMR is a strong predictor of inferior graft survival: 1] ^AMR vs no AMR – 1y GS 60% vs 89% (Lefaucheur et al); 2]

Abbreviations: ANZDATA – Australia and New Zealand Dialysis and Transplant registry, AMR – antibody mediated

**Table 4.** Incidence of antibody mediated rejection and graft survival following positive crossmatch kidney

*Lefaucheur et al ^* [26] 43 35 89 89

*Magee et al* [71] 28 39 92 89 *Gloor et al* [106] 119 41 89 89 *Haririan et al* [106] 41 12 90 85 *Vo et al* [72] 16 30 94 Not reported *Vo et al#* [62] 76 29 87 84

**(%)**

95 96 **2-year graft survival (%)**

> 93 96

**Number of**

550 296

AMR vs no AMR – development of transplant glomerulopathy 44% and 12% (Gloor et al).

**HLA antibodies**

116 Current Issues and Future Direction in Kidney Transplantation

*Thielke et al*<sup>θ</sup>

ANZDATA 2010\* [107] Primary DD grafts Primary LD grafts

rejection, DD – deceased donor, LD – live-donor.

transplants].

transplantation.

θ



and a 1g dose of rituximab (day 15) reduced the deceased donor transplant wait-list time from 95±46 months to 4.2±4.5 months achieving acceptable rejection rates and graft survival at 24 months [62]. In contrast, a recent prospective cohort study evaluating pre-transplant desensi‐ tization with two doses of IVIg (2 g/kg up to a maximum of 120g per dose) plus a single dose

Detection of Antibody-Mediated Rejection in Kidney Transplantation and the Management of Highly Sensitised…

panel reactive antibody (cPRA) of >90% and had spent >5 years on the deceased donor waitlist did not improve their transplant potential or reduced class I and II cPRA levels. This finding has been corroborated by other studies that have demonstrated that treatment with high dose IVIg in highly sensitized patients (flow cytometric calculated PRA of 100%) on the deceased donor transplant wait-list did not significantly alter their cPRA levels or improved their transplant potential highlighting that the potential benefit of desensitization of highly sensitized transplant candidates on the deceased donor wait-list remain uncertain [63-65].

The optimal desensitization regimen for highly sensitized renal transplant candidates in the context of living related and unrelated donation remains unclear. Most of the current desen‐ sitization protocols are modifications of plasmapheresis and intravenous immunoglobulin (IVIg) ± rituximab and have been used successfully to desensitize highly allo-sensitized transplant candidates, therefore allowing transplantation to occur [61, 66-73] (Table 2). However, desensitization of positive CDC or flow cytometric cross-match patients using immunoadsorption with rituximab followed by ongoing immunoadsorption post-transplant appears promising achieving rapid elimination of DSA and excellent short-term graft out‐ comes [74]. Immunoadsorption appears to be more effective than plasmapheresis in removing circulating DSA and studies have shown that a single pre-transplant immunoadsorption could render a positive cross-match to become negative [75, 76]. Encouraging results have been obtained with the use of bortezomib and/or eculizumab in desensitization protocols to achieve successful transplantation across a positive CDC and/or flow cytometric cross-match barrier but the use of these agents are usually considered adjunctive treatments to standard protocol [77]. Although splenectomy has historically been used in the desensitization protocols for ABO-incompatible transplants and treatment of refractory AMR by removing an essential source of B lymphocytes, this has largely been superseded by B cell depleting agents [78]. These techniques aim to lower the DSA to an 'acceptable' level pre-transplant to allow transplanta‐ tion to proceed and preventing immediate acute renal allograft injury. Most published studies of desensitization protocols are non-randomized and observational with varying techniques and threshold of detecting pre-transplant DSA, thereby making comparisons between studies difficult. Plasmapheresis with low dose IVIg (0.1g/kg following each plasmapheresis) for 2-3 weeks pre-transplant followed by interleukin-2 receptor antibody or CD3-T cell depletive agent induction is the most common desensitization protocol utilized in many transplanting centres although the duration of treatment pre- and post-transplant would depend on achieving a negative cross-match pre-transplant and on the DSA titres. Studies utilizing this protocol have reported high risk of AMR (between 12-100%) with a reduction in longer-term graft survival (66% at 4 years) despite acceptable short-term graft survival [69, 79, 80]. Although high-dose IVIg (2g/kg) was initially considered for deceased donor kidney trans‐ plant candidates, it has been implemented with and without rituximab in positive CDC and/or flow cytometric cross-match live-donor transplant candidates with similar risk of

) in highly sensitized kidney transplant candidates with a calculated

http://dx.doi.org/10.5772/54735

119

of rituximab (375 mg/m2

Abbreviations: LD = live-donor, DD – deceased donor, CDC – complement dependent cytotoxicity, FCMX – flow cytometric cross-match, DSA – donor specific antibody, PP – plasmapheresis, AR – acute rejection, rATG – rabbit antithymocyte globulin, GS – graft survival, DCGF – death-censored graft failure, PS – patient survival, AR – acute rejection, AMR – antibody mediated rejection, ACR – acute cellular rejection, TG – transplant glomerulopathy, IVIg – intravenous immunoglobulin, PNF – primary non-function, CMV – cytomegalovirus

**Table 5.** Relevant studies of desensitization in live and deceased-donor transplantation.

Studies reporting the utilization of desensitisation techniques to allow transplantation in highly sensitized transplant candidates have focussed predominantly on live-donor trans‐ plantation, which allows early planning and implementation of treatment at a suitable time (Table 5). A recent paper by *Montgomery R et al* had demonstrated that desensitization of highly sensitized patients for live-donor transplantation was associated with a significant survival benefit compared with waiting for a compatible deceased donor organ. By 8 years, this survival advantage more than doubled suggesting that desensitization protocols to overcome incom‐ patibility barriers in live-donor renal transplantation may be justified [58]. However, the benefit of desensitization of highly sensitized patients on the deceased donor transplant waitlist remains debatable due to the uncertainty of kidney availability [59, 60]. The only random‐ ized study evaluating the benefit of IVIg to improve transplant potential in highly sensitized transplant candidates on the deceased donor transplant wait-list was a double-blind, placebocontrolled, multicentre study whereby 101 patients with PRA >50% who have been waiting for >5 years on the transplant wait-list were randomized to receive IVIg (2g/kg monthly for 4 months) or placebo. The administration of high-dose IVIg was associated with a reduction in PRA levels with 35% of IVIg-treated patients being transplanted compared with 17% of patients receiving placebo suggesting that this regimen was associated with improved transplant potential for highly sensitized patients [61]. This same group modified this initial regimen by adding rituximab and subsequently reported that desensitization of highly sensitized patients with PRA >30% using high dose IVIg (2 doses of of 2 g/kg days 1 and 30) and a 1g dose of rituximab (day 15) reduced the deceased donor transplant wait-list time from 95±46 months to 4.2±4.5 months achieving acceptable rejection rates and graft survival at 24 months [62]. In contrast, a recent prospective cohort study evaluating pre-transplant desensi‐ tization with two doses of IVIg (2 g/kg up to a maximum of 120g per dose) plus a single dose of rituximab (375 mg/m2 ) in highly sensitized kidney transplant candidates with a calculated panel reactive antibody (cPRA) of >90% and had spent >5 years on the deceased donor waitlist did not improve their transplant potential or reduced class I and II cPRA levels. This finding has been corroborated by other studies that have demonstrated that treatment with high dose IVIg in highly sensitized patients (flow cytometric calculated PRA of 100%) on the deceased donor transplant wait-list did not significantly alter their cPRA levels or improved their transplant potential highlighting that the potential benefit of desensitization of highly sensitized transplant candidates on the deceased donor wait-list remain uncertain [63-65].

**Number Technique Outcomes Complications**

• Improved DD transplant rate in IVIg group compared to placebo (31% vs 12%, • More headaches in

IVIg group

• Not reported

• Estimated projected mean time to transplantation is 4.8y for IVIG vs 10.3y for

• GS and PS similar

• 31% AR (<1m), 38% ATG and 23% graft loss

• 2y GS 89%, PS 98%

p=0.01)

placebo

from AR

• IVIg 2g/kg monthly for 4 months or placebo

• DD monthly 2g/kg IVIg x 4 + pre-Tx 2g/kg

Abbreviations: LD = live-donor, DD – deceased donor, CDC – complement dependent cytotoxicity, FCMX – flow cytometric cross-match, DSA – donor specific antibody, PP – plasmapheresis, AR – acute rejection, rATG – rabbit antithymocyte globulin, GS – graft survival, DCGF – death-censored graft failure, PS – patient survival, AR – acute rejection, AMR – antibody mediated rejection, ACR – acute cellular rejection, TG – transplant glomerulopathy, IVIg – intravenous

Studies reporting the utilization of desensitisation techniques to allow transplantation in highly sensitized transplant candidates have focussed predominantly on live-donor trans‐ plantation, which allows early planning and implementation of treatment at a suitable time (Table 5). A recent paper by *Montgomery R et al* had demonstrated that desensitization of highly sensitized patients for live-donor transplantation was associated with a significant survival benefit compared with waiting for a compatible deceased donor organ. By 8 years, this survival advantage more than doubled suggesting that desensitization protocols to overcome incom‐ patibility barriers in live-donor renal transplantation may be justified [58]. However, the benefit of desensitization of highly sensitized patients on the deceased donor transplant waitlist remains debatable due to the uncertainty of kidney availability [59, 60]. The only random‐ ized study evaluating the benefit of IVIg to improve transplant potential in highly sensitized transplant candidates on the deceased donor transplant wait-list was a double-blind, placebocontrolled, multicentre study whereby 101 patients with PRA >50% who have been waiting for >5 years on the transplant wait-list were randomized to receive IVIg (2g/kg monthly for 4 months) or placebo. The administration of high-dose IVIg was associated with a reduction in PRA levels with 35% of IVIg-treated patients being transplanted compared with 17% of patients receiving placebo suggesting that this regimen was associated with improved transplant potential for highly sensitized patients [61]. This same group modified this initial regimen by adding rituximab and subsequently reported that desensitization of highly sensitized patients with PRA >30% using high dose IVIg (2 doses of of 2 g/kg days 1 and 30)

*Jordan S et al* [61]

*Jordan S et al* [111]

• 98 PRA ≥50% randomised 1:1 to IVIg or placebo (LD and DD)

118 Current Issues and Future Direction in Kidney Transplantation

• N=42 (62% LD) • LD 1x 2g/kg IVIg

immunoglobulin, PNF – primary non-function, CMV – cytomegalovirus

IVIg

**Table 5.** Relevant studies of desensitization in live and deceased-donor transplantation.

The optimal desensitization regimen for highly sensitized renal transplant candidates in the context of living related and unrelated donation remains unclear. Most of the current desen‐ sitization protocols are modifications of plasmapheresis and intravenous immunoglobulin (IVIg) ± rituximab and have been used successfully to desensitize highly allo-sensitized transplant candidates, therefore allowing transplantation to occur [61, 66-73] (Table 2). However, desensitization of positive CDC or flow cytometric cross-match patients using immunoadsorption with rituximab followed by ongoing immunoadsorption post-transplant appears promising achieving rapid elimination of DSA and excellent short-term graft out‐ comes [74]. Immunoadsorption appears to be more effective than plasmapheresis in removing circulating DSA and studies have shown that a single pre-transplant immunoadsorption could render a positive cross-match to become negative [75, 76]. Encouraging results have been obtained with the use of bortezomib and/or eculizumab in desensitization protocols to achieve successful transplantation across a positive CDC and/or flow cytometric cross-match barrier but the use of these agents are usually considered adjunctive treatments to standard protocol [77]. Although splenectomy has historically been used in the desensitization protocols for ABO-incompatible transplants and treatment of refractory AMR by removing an essential source of B lymphocytes, this has largely been superseded by B cell depleting agents [78]. These techniques aim to lower the DSA to an 'acceptable' level pre-transplant to allow transplanta‐ tion to proceed and preventing immediate acute renal allograft injury. Most published studies of desensitization protocols are non-randomized and observational with varying techniques and threshold of detecting pre-transplant DSA, thereby making comparisons between studies difficult. Plasmapheresis with low dose IVIg (0.1g/kg following each plasmapheresis) for 2-3 weeks pre-transplant followed by interleukin-2 receptor antibody or CD3-T cell depletive agent induction is the most common desensitization protocol utilized in many transplanting centres although the duration of treatment pre- and post-transplant would depend on achieving a negative cross-match pre-transplant and on the DSA titres. Studies utilizing this protocol have reported high risk of AMR (between 12-100%) with a reduction in longer-term graft survival (66% at 4 years) despite acceptable short-term graft survival [69, 79, 80]. Although high-dose IVIg (2g/kg) was initially considered for deceased donor kidney trans‐ plant candidates, it has been implemented with and without rituximab in positive CDC and/or flow cytometric cross-match live-donor transplant candidates with similar risk of rejection and graft survival to studies using plasmapheresis and low-dose IVIg [62, 80-82]. A retrospective study by *Stegall et al* showed that CDC T cell cross-match positive renal transplant recipients receiving high dose IVIg alone had a higher rate of AMR [80%) compared to recipients receiving plasmapheresis, low-dose IVIg with rituximab (37%) or plasmapheresis, low-dose IVIg, rituximab and pre-transplant anti-thymocyte globulin (29%) suggesting that high dose IVIg may be inferior to the combination of plasmapheresis and IVIg but it is difficult to draw any firm conclusion from an uncontrolled study [73]. Furthermore, there are sugges‐ tions that pre-transplant treatment to lower DSA MFI to <6000 using Luminex is recommended for successful transplantation and is associated with lower risk of AMR but again, this remains debatable [14].

**Treatment Actions Complications Cost Comments**

Thrombotic events Acute renal failure Haemolytic anaemia Aseptic meningitis Anaphylactoid reactions

Detection of Antibody-Mediated Rejection in Kidney Transplantation and the Management of Highly Sensitised…

Hypotension Bleeding diathesis Potential blood-borne pathogen transmission if replacement with fresh frozen plasma is required

(rare)

Similar complications as plasmapheresis

Infection (fungal and other opportunistic) Progressive multifocal leukoencephalopathy

Fatigue, weakness Gastrointestinal

(mild, transient)

transient)

(rare, severe)

leukopenia

disturbances (common, mild) Anaemia, thrombocytopenia

Peripheral neuropathy (mild,

Meningococcal infections

Other infections especially with encapsulated bacteria Anaemia (rarely serious),

Hypertension, headache, gastrointestinal upset (common, mild)

US\$8700 for 120g

US\$2000 per session

US1600 per session

US\$3900 for 700mg

US\$1322 for 3.5mg

US\$5990 per 300mg rate

Infusion related adverse events related to osmolality, minimized by slowing infusion

http://dx.doi.org/10.5772/54735

121

Reduce thrombotic events by using aspirin, heparin/ enoxaparin, intravenous fluids Newer preparation, isoosmolar products have higher titres of antiA±B, resulting in higher rates of haemolysis

Non-selective removal of

Higher plasma volume exchange resulting in higher antibody removal rate may be achieved over plasmapheresis. More selective IgG removal compared to plasmapheresis

Similar effectiveness using

Role in desensitization unclear

Role in desensitization unclear Requires meningococcal vaccination at least 2 weeks prior to transplant

smaller dose

antibodies

Neutralize circulating anti-

Enhance clearance of anti-

Induce B cell apoptosis Inhibitory effects on other immune cells such as macrophages and natural killer cells by binding to their

Removal of circulating anti-

Removal of circulating anti-

Chimeric murine/human monoclonal antibody that binds to CD20 on pre-B and mature B lymphocytes

Proteasomal inhibitor causing apoptosis of plasma cells

Humanized monoclonal antibody against C5 preventing the formation of membrane attack complex

(C5b-9)

Abbreviation: HLA – human leukocyte antigens.

**Table 6.** Complications and cost of desensitization treatment.

HLA antibodies

HLA antibodies Inhibit complement activation

Fcγ receptors

HLA antibodies

HLA antibodies

Intravenous immunoglobulin [112]

Plasmapheresis [113]

Immunoadsorption [74, 114]

Rituximab [115]

Bortezomib [116, 117]

Eculizumab [118, 119]

Following successful transplantation, ongoing monitoring of DSA and early recognition of AMR is crucial to avoid early graft loss. On re-exposure to donor antigens against which the recipient is sensitized, memory B lymphocytes in their spleen, bone marrow and lymph nodes undergo an anamnestic reaction leading to the development of antibody-producing cells, which can produce high levels of DSA within days or weeks and therefore, positive crossmatch kidney transplantation requires both pre- and post-transplant interventions to contin‐ ually suppress DSA levels. Although continuing plasmapheresis and/or IVIg post-transplant following successful desensitization of highly sensitized recipients with positive cross-match against the donor is generally accepted, there has been no study addressing the type, amount, duration and cost-effectiveness of such approach [70]. Nevertheless, studies have demonstrat‐ ed a strong association between the development of *de novo* DSA (especially DQ-DSA or when there is a rise of DSA >500 MFI) and AMR and graft loss suggesting that that long-term monitoring of DSA in highly sensitized patients may be appropriate, especially those receiving class II-incompatible grafts [83-85]. A recent single centre study suggested that post-transplant DSA surveillance followed by pre-emptive initiation of IVIg and plasmapheresis with rising DSA titres have successfully improved long-term graft survival [86].

Intravenous gammaglobulins (IVIG) are effective in the successful management of a number of autoimmune and inflammatory disorders attributed to their immunomodulatory and immunoregulatory properties. IVIG has been suggested in the management of highly sensi‐ tized renal transplant patients because it eliminates eliminate circulating anti-HLA antibodies, suppresses the production of these antibodies by inducing B cell apoptosis (and also T cells and monocytes *in vitro*) and is a modifier of complement activation and injury [87, 88]. There is now considerable debate among the transplant community regarding the balance between the benefits and harms associated with IVIG desensitising patients with high immunological risks. t[89, 90]. One small but significant side effect associated with the use of high dose IVIg is the risk of thrombosis, which may be mitigated by slowing infusion rate (maximum infusion rate of 100mg/kg/hour), aspirin, enoxaparin and intravenous hydration pre- and post-infusion [91]. The important side effects of IVIg along with other agents commonly used in the desensitization protocol are summarized in Table 6. However, it is important to note that many of the side effects associated with desensitization treatment have been reported in nontransplant population but should be recognized and advised to patients receiving these treatments.

Detection of Antibody-Mediated Rejection in Kidney Transplantation and the Management of Highly Sensitised… http://dx.doi.org/10.5772/54735 121


Abbreviation: HLA – human leukocyte antigens.

rejection and graft survival to studies using plasmapheresis and low-dose IVIg [62, 80-82]. A retrospective study by *Stegall et al* showed that CDC T cell cross-match positive renal transplant recipients receiving high dose IVIg alone had a higher rate of AMR [80%) compared to recipients receiving plasmapheresis, low-dose IVIg with rituximab (37%) or plasmapheresis, low-dose IVIg, rituximab and pre-transplant anti-thymocyte globulin (29%) suggesting that high dose IVIg may be inferior to the combination of plasmapheresis and IVIg but it is difficult to draw any firm conclusion from an uncontrolled study [73]. Furthermore, there are sugges‐ tions that pre-transplant treatment to lower DSA MFI to <6000 using Luminex is recommended for successful transplantation and is associated with lower risk of AMR but again, this remains

Following successful transplantation, ongoing monitoring of DSA and early recognition of AMR is crucial to avoid early graft loss. On re-exposure to donor antigens against which the recipient is sensitized, memory B lymphocytes in their spleen, bone marrow and lymph nodes undergo an anamnestic reaction leading to the development of antibody-producing cells, which can produce high levels of DSA within days or weeks and therefore, positive crossmatch kidney transplantation requires both pre- and post-transplant interventions to contin‐ ually suppress DSA levels. Although continuing plasmapheresis and/or IVIg post-transplant following successful desensitization of highly sensitized recipients with positive cross-match against the donor is generally accepted, there has been no study addressing the type, amount, duration and cost-effectiveness of such approach [70]. Nevertheless, studies have demonstrat‐ ed a strong association between the development of *de novo* DSA (especially DQ-DSA or when there is a rise of DSA >500 MFI) and AMR and graft loss suggesting that that long-term monitoring of DSA in highly sensitized patients may be appropriate, especially those receiving class II-incompatible grafts [83-85]. A recent single centre study suggested that post-transplant DSA surveillance followed by pre-emptive initiation of IVIg and plasmapheresis with rising

Intravenous gammaglobulins (IVIG) are effective in the successful management of a number of autoimmune and inflammatory disorders attributed to their immunomodulatory and immunoregulatory properties. IVIG has been suggested in the management of highly sensi‐ tized renal transplant patients because it eliminates eliminate circulating anti-HLA antibodies, suppresses the production of these antibodies by inducing B cell apoptosis (and also T cells and monocytes *in vitro*) and is a modifier of complement activation and injury [87, 88]. There is now considerable debate among the transplant community regarding the balance between the benefits and harms associated with IVIG desensitising patients with high immunological risks. t[89, 90]. One small but significant side effect associated with the use of high dose IVIg is the risk of thrombosis, which may be mitigated by slowing infusion rate (maximum infusion rate of 100mg/kg/hour), aspirin, enoxaparin and intravenous hydration pre- and post-infusion [91]. The important side effects of IVIg along with other agents commonly used in the desensitization protocol are summarized in Table 6. However, it is important to note that many of the side effects associated with desensitization treatment have been reported in nontransplant population but should be recognized and advised to patients receiving these

DSA titres have successfully improved long-term graft survival [86].

debatable [14].

120 Current Issues and Future Direction in Kidney Transplantation

treatments.

**Table 6.** Complications and cost of desensitization treatment.

In the absence of large randomized controlled trials, the optimal desensitization protocol is unclear. Observational data have reported desensitization protocols comprising of high or low-dose IVIg and plasmapheresis with or without rituximab and othetr newer agents such as bortezomib and eculizumab may be beneficial in selected patients, the rate of AMR remains extremely high (up to 50% in pre-sensitized positive cross-match patients undergoing desensitization) and may not be justified in circumstances such as in patients with very strong pre-transplant DSA levels [19]. The lack of treatment effectiveness among highly sensitised individuals is not unexpected, because most recommended treatment options such as plas‐ mapheresis, IVIg and rituximab have minimal effects on plasma cells, the critical element of anti-HLA antibodies production, and AMR. Clinicians should discuss with their patients about the complexities and the potential side effects associated with any desensitisation protocols, taking into considerations the underlying immunological risks of the potential transplant candidates, the potential benefits against the short and longer-term harms such as infection and cancer risks. Specifically transplant candidates with prior sensitizing events and have DSA (even at low levels) against potential donor (e.g. husband to wife transplant) are at significant risk of AMR after transplantation despite r adequate desensitization. If desensitization is undertaken, this should be initiated 2-3 weeks post-transplant to ensure adequate removal of anti-HLA DSA pre-transplant with at least a negative CDC cross-match (or reduction in flow cytometric cross-match results) and persistent reduction in DSA MFI below 2000-5000. Transplantation should be abandoned if there is rebound of high titres DSA and/or the crossmatches remained unchanged/positive following desensitisation protocols. Although the benefit or cost-effectiveness of post-transplant DSA monitoring ± protocol biopsies in improv‐ ing post-transplant graft outcomes remains unclear, it is well established that *de novo* DSA and rising pre-transplant DSA are associated with a greater risk of rejection and poorer graft survival [32, 92, 93]. However, there is no data suggesting that early interventions in renal transplant recipients who develop *de novo* DSA or rising DSA would result in an improvement in graft outcomes. Nevertheless, prospective monitoring of pre-existing DSA or for *de novo* DSA ± protocol biopsies should be considered and appropriate treatment instituted in those who develop histological evidence of rejection. Several proposed desensitization and posttransplant follow-up algorithms for positive cross-match highly sensitized recipients are available but the cost-effectiveness and outcomes of these programs remains unknown [80].

list as a result of prior sensitizing events, future studies addressing all these unanswered issues

Detection of Antibody-Mediated Rejection in Kidney Transplantation and the Management of Highly Sensitised…

, Rebecca Lucy Williams1

1 Department of Renal Medicine, Sir Charles Gairdner Hospital, Perth, Australia

2 School of Medicine and Pharmacology, University of Western Australia, Perth, Australia

3 Sydney School of Public Health, University of Sydney; Centre for Kidney Research, The Children's Hospital at Westmead; Centre for Transplant and Renal Research, Westmead

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\*Address all correspondence to: wai.lim@health.wa.gov.au

, Germaine Wong3

and

http://dx.doi.org/10.5772/54735

123

are critical.

**Author details**

Wai Hon Lim1,2\*

**References**

6): 28.

Shyam Dheda1,2, Siew Chong1

Hospital, Sydney, Australia

Med Assoc 1993; 45 (2): 77.

### **7. Conclusion**

Despite the availability of more potent immunosuppression, the incidence of AMR continues to be an important cause of graft loss. Nevertheless, with the evolution of more sensitive molecular-based HLA-typing and the ability to detect DSA, clinicians have the necessary facts to critically appraise the immunological risk of each transplant candidate. However, there continues to be debate on several major issues including the role of non-DSA in transplantation, the appropriate DSA threshold, complexity in the diagnosis of acute and chronic AMR and the optimal desensitization protocol for highly sensitized patients. As there continues to be an increase in the number of highly sensitized renal transplant candidates on the transplant waitlist as a result of prior sensitizing events, future studies addressing all these unanswered issues are critical.
