Impact of immunosuppression on HLA-antibody formation

1. The prevalence of HLAabs was 25% in the entire population, with a similar distribution for class I and class II. 2. For kidney transplant recipients the prevalence of HLAabs was 25.7 % and the prevalence of de novo HLAabs was 19.8 % in patients without preformed antibodies. 3. Patients with less than 5 years from transplant to blood sampling had lesser HLAabs. The WS were on 2002 and 2004, and then those patients were transplanted after 1997 when TAC was routinely used in some centers. 4. In patients transplanted after 1992, the prevalence of HLAabs was lower and it is consistent with the incorporation of the new IS drugs (TAC was introduced around 1994). 5. For kidney transplantation, the use of cyclosporine plus rapamune had the strongest protector effect for the presence of HLAabs, followed by tacrolimus and cyclosporine group. 6. This protective effect is diminished in patients with female gender, history of previous transplant, and pre-transplant positive PRA. 7. For kidney transplantation, the presence of HLAabs was associated with a higher rate of graft loss (P < 0.0001, HR = 2.26, 95% CI 2.11 - 3.36) but not with patient survival. 8. Patients with liver transplantation showed the lowest prevalence of HLAabs with only 9.6 % and similar distribution for both classes. The presence of HLAabs was not associated with patient or graft survival in Liver Transplantation. 9. For heart and lung transplantation, a posttransplant positive test for HLAabs was associated with worse graft survival, similar to kidney transplantation, with a HR = 3.05 and 3.87 respectively.