**3. Endoscopic examination and Peyer's patch response**

Endoscopically, elevation of the small intestinal mucosa may be recognized and biopsied when clinical rejection is suspected. Since this elevation is observed in patients who are not receiving oral nutrition, the change may not be the result of irritation from the lumen of the small intestine and more likely due to the reaction of the Peyer's patches (PPs) to a load of patient cells on the graft mucosal immune system. In our cases, the biopsied Peyer's patches were injured at the onset of ACR (**Figures 3A** and **B**). Therefore, PP is one of the targets of ACR or other types of rejection (**Figure 3C**). Notably, B cells increased in number in the disintegrated PPs (**Figure 3**). As described later, IL-5 was increased in the intestinal allograft [17], which may promote the transient B cell growth in PP.

#### **Figure 3.**

*Histology of a PP in an intestinal allograft. (A, B) A hyperplastic Peyer's patch stained with CD79a antibody before ACR (A) and at the onset of ACR (B). (C) CD8 staining of PP after 42 h at the onset of rejection. Many CD8+ CTLs infiltrate in PP. CD79 and CD8 were visualized by DAB. The photo magnitude is 100×.*

**93**

**Figure 4.**

*increased 48 h after the onset of ACR. (G) CD1d+*

*Pathology of Intestinal Transplantation: Rejection and a Case of Tolerance*

Here we review cases of SBT at Kyoto University Hospital [17, 18, 21, 22]. SBT was performed owing to intestinal malrotation and Hirschsprung's disease-related

Jejunal or ileal grafts were monitored histologically. When fever, increased intestinal juice, abdominal pain, or C-reactive protein (CRP) elevation in peripheral blood (>0.5 mg/10−1 L) was observed, an endoscopic examination was performed. In particular, for the first 1 to 2 weeks after surgery, the examination was performed every other day, and a histological examination was also performed. Once the condition of the patient became stable, a histological examination was performed approximately once a week, and the state of the intestinal graft was monitored continuously for up to 2 months in the hospital. The patient received immunosuppressive therapy in combination with tacrolimus (trough concentration: 20 ng/mL) and methylprednisolone (30 mg/kg/day, 1 to 3 times). In the biopsy examination, diagnosis by hematoxylin and eosin staining and findings specific to rejection within 6 h were confirmed by immunostaining of frozen sections. For histological diagnosis, we stained the apoptosis-related proteins such as FasL and surface antigens of B cells, T cells, and NK cells in each case. Steroid pulse therapy was conducted following

*Immunofluorescent staining of natural killer T cells in the intestinal allograft. Immunostaining of an intestinal allograft. Green signal, FITC and red signal, phycoerythrin [PE]. Nuclei are stained with DAPI (blue). Brown signal was visualized with DAB. (A) TCRV*α*24 (200×) and (B) TCR*β*11 (200×). (C, D) TCRV*α*24 (green) and IL-4 (red) (IL-4 positive iNKT is indicated by an arrow). The observation magnification is 200× in both cases. (E, F) TCRV*α*24 (red) and TUNEL (green). (E) TUNEL+ (apoptotic) TCRV*α*24 + iNKT cells are observed at the onset of ACR (100×) and (F) 48 h after the onset of ACR (100×). Doubly stained cells were* 

*red, respectively. (H) TCRV*α*24 stained iNKT cells (red) and CD1d stained dendritic cells (green). (I) FasL+* 

*(green) TCRV*α*24+ (red) iNKT cells. The observation magnification is 400 x in (G)-(I)."*

 *dendritic cells. CD1d and CD11c were stained green and* 

*DOI: http://dx.doi.org/10.5772/intechopen.94361*

**4. Cases at Kyoto University Hospital**

effects (**Figure 4**).
