**3.2 Universal donor phenomenon: the need to implement a policy of universal haemolysin testing of group O donor units**

ABO blood group system is one of the most clinically relevant blood group systems. Individuals above the age of 6 months have clinically significant anti-A and/or anti-B in their serum particularly if they lack the corresponding antigens on their red cells. Whole blood transfusion still thrives in Nigeria despite the advantages of component therapy and challenges associated with whole blood transfusion (development of febrile transfusion reactions, graft-versus-host disease, alloimmunization to leukocyte antigens, immunomodulatory effects, transmission of diseases such as cytomegalovirus, Human T-Lymphotrophic Virus I/II and Epstein Barr (EBV) for which leukocytes may be the vector) [68]. Blood group O donor blood is the most common blood group among Nigerian blood donors [69] and their red cells are commonly used as universal donor units for transfusion to A, B and AB recipient particularly in emergency situations. Blood group O individuals lack the A and B antigens on their red cells and thus are inappropriately called Universal donors. These individuals have anti A and Anti B in the plasma. Due to the absence of A and B on their red cell, their red cells could be given to A, B, and AB individuals. This is quite useful particularly in Nigeria and other developing countries where there is inadequate supply of donor blood. However, some group O individuals have potentially lytic anti-A and lytic anti-B in their plasma that bind to antigens A and B on the surface of erythrocytes in recipients and potentially activate the complement cascade resulting in acute intravascular haemolysis. To avoid this, all blood group O donor units intended for transfusion to non-O patient must be tested for the presence of these anti-A and lytic anti-B haemolysis. Those donors found negative can have their blood given to non-O patients while those that test positive are reserved for group O recipients only. Haemolysin testing to

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that require red cell transfusion.

*Distribution of Clinically Relevant Blood Group Antigens among Nigerians…*

identify the presence of haemolytic anti-A and anti-B antibodies has emerged as a useful screening in most countries to identify high levels of anti-A and/or anti-B antibodies to prevent HTRs. Routine haemolysis testing of blood group O donor units intended for transfusion to A, B or AB recipient is not routinely carried out in most settings in Nigeria despite the high prevalence of haemolysins observed among Nigerians in previous studies [70–75]. The Nigeria government can learn from evidenced-based best practices in most developed settings [76, 77] and implement a policy to routinely test all group O donor units for haemolysins in other to identify group O donors with high titre of IgG anti A and/or anti B whose blood should be reserved only for transfusion to group O recipient while those that test negative can be transfused to A, B or AB individual as a way to maximising the use

Alloantibodies are antibodies produced in a patient as a result of exposure to foreign red cell antigen via transfusion, pregnancy or transplantation. In countries such as Nigeria, there are multiple ethnic groups and racial or genetic heterogeneity among the population. This can often be associated with a wide variation of alloantibodies [78]. Other common factors that facilitate alloantibody formation in the recipient include: the immune competence, the dose of the antigen the recipient is exposed to, the route of exposure and how immunogenic the foreign antigen is [79, 80]. Development of alloantibodies can lead to difficulty in finding compatible blood for transfusion or it can result in severe delayed haemolytic transfusion reaction if the antibody titre is low, undetected, missed and if antigen positive units is transfused [81]. Evidenced-based best practice in the developing world requires that alloantibody testing is carried out as part of pre-transfusion testing of patients who require a red cell transfusion as well as pregnant women presenting to antenatal clinic at booking [82, 83]. The aim of this test is to detect the presence of unexpected red cell antibody in the patient's serum [84, 85]. Once these antibodies are detected during the alloantibody screening, every effort must be made to identify the specificity of the alloantibody by doing a panel test. The aim of identifying the specificity of the alloantibody in a patient that requires a red cell transfusion is to enable the Medical Laboratory or Biomedical Scientist to select antigen negative donor unit for appropriate crossmatch (indirect antiglobulin test) for such patient [86]. The aim of a panel test in the case of a pregnant women coming for antenatal booking is to identify the alloantibody, determine whether the antibody can potentially cause HDFN [87] and to allow the monitoring of the titre or quantification of the antibody every 4 weeks from booking until 28 weeks' gestation and every 2 weeks thereafter until delivery [88]. The obstetrician requires this information to determine to what extent the developing foetus is affected by HDFN, decide whether to monitor the baby for anaemia using Doppler ultrasound, determine whether the baby will require intrauterine transfusion and to make an informed decision to possibly deliver the baby earlier. These evidence-based best practices are not being implemented in many settings in Nigeria. Testing of donor units for other clinically relevant red cell antigens other than ABO and Rhesus D is not routinely carried out. Also, donor units particularly those intended for transfusion to pregnant women and neonates are also not routinely screened for CMV and Hepatitis E virus like it is routinely done in more advanced part of the world. This is a complete failure in stewardship by the Nigerian government and can compromise the transfusion service delivery to pregnant women and patients

*DOI: http://dx.doi.org/10.5772/intechopen.90372*

of our limited allogeneic stock.

**3.3 Screening for clinically significant alloantibodies**

*Distribution of Clinically Relevant Blood Group Antigens among Nigerians… DOI: http://dx.doi.org/10.5772/intechopen.90372*

identify the presence of haemolytic anti-A and anti-B antibodies has emerged as a useful screening in most countries to identify high levels of anti-A and/or anti-B antibodies to prevent HTRs. Routine haemolysis testing of blood group O donor units intended for transfusion to A, B or AB recipient is not routinely carried out in most settings in Nigeria despite the high prevalence of haemolysins observed among Nigerians in previous studies [70–75]. The Nigeria government can learn from evidenced-based best practices in most developed settings [76, 77] and implement a policy to routinely test all group O donor units for haemolysins in other to identify group O donors with high titre of IgG anti A and/or anti B whose blood should be reserved only for transfusion to group O recipient while those that test negative can be transfused to A, B or AB individual as a way to maximising the use of our limited allogeneic stock.
