Common RBC antigens in O type Tunisian blood donors and their importance in alloimmunization.

BACKGROUND: The presence of some red blood cell (RBC) antigens may affect the preference for using type O blood in emergency situations because they may induce complex or multiple alloimmunization in special circumstances. METHODS: A subgroup of 77 type O blood Tunisian donors were genotyped for 19 common blood alleles using the single specific primer-polymerase chain reaction method. The statistical analysis was done using HaploView software. RESULTS: The study showed the dominance of the alleles RH*5, KEL*2, FY*2, and CO*1 and the absence of the homozygous state of the KEL*1 and CO*2 alleles. Furthermore, a complete linkage disequilibrium between the RH*2/RH*4 and RH*3/RH*5 loci and the FY*Null/FY*Exp and FY*A/FY*B loci was detected. Additionally, it seems that sensitization to MNS:3, FY:1, and RH:3 may constitute a potential factor for alloimmunization after transfusion with O blood type units: the probabilities of simple alloimmunizations are 24.5 per 100, 18.5 per 100, and 18 per 100, respectively. Multiple alloimmunization against RH:1;KEL:1 or RH:1;KEL:1;RH:3 phenotypes may occur, with probabilities of 7 per 1000 and 2 per 1000, respectively. CONCLUSION: Some O-type RBC units may contain blood with very immunogenic phenotypes, the use of which in an emergency requires great caution because it can be a step towards subsequent alloimmunization.

The CD28 IVS3 + 17 T/C polymorphism and the GVHD occurrence in Tunisian patients receiving an HLA-identical sibling HSCs transplant.

Graft-versus-host disease (GVHD) is a potentially serious complication ofallogeneic hematopoietic stem cell transplantation (HSCT). Graft-contaminating T cells (donor T cells) arecrucial for the development ofGVHD since they are able to react against the recipient's antigens. In this study we aim toevaluatethepotentialassociation between the IVS3 + 17 T/C gene variation in the CD28 molecule, a T cells costimulatory factor, and the GVHD occurrence in a Tunisian group of recipients of allo-HSCTs. Results show that there is an association between the presence of this polymorphism and the occurrence of grades II-IV acute GVHD (OR: 2.470, I.C: 1.027-5.938, p = 0.043). As for the chronic GVHD, it seems that the studied gene variation has no impact on the occurrence of this complication, which appeared likely to be affected by the HSCT graft source (PBSC: peripheral blood stem cells) (OR: 5.141, I.C: 1.590-16.620, p = 0.006). Based on these data, we believe that the CD28 IVS3 + 17 T/C polymorphism is a significant factor in the pathogenesis of acute GVHD.

[Rare red blood group discovered by a blood group discrepancy: a case report]. / Découverte d'un phénotype érythrocytaire rare suite à une difficulté de groupage : à propos d'un cas.

ABO typing is essential for preventing ABO incompatibility transfusion reactions. Discrepancy exists when reactions in forward grouping do not match with reverse grouping. Any discrepancies reported should be investigated so that correct blood group is reported minimizing the chances of transfusion reaction. The most common causes of ABO discrepancy are cold autoantibodies and missing serum reactivity. We report a rare alloantibody anti-PP1Pk discovered during the resolution of a grouping difficulty with a positive control. Anti-PP1Pk is associated with hemolytic transfusion reactions. In our observation, we were faced with transfusional impasse because of the unavailability of a national rare blood bank or a compatible donor on the registry of individuals with a rare blood phenotype.