INFLUENCE OF HLA-DRB1-ASTERISK INCOMPATIBILITY ON THE OCCURRENCE OF REJECTION EPISODES AND GRAFT-SURVIVAL IN SEROLOGICALLY HLA-DR-MATCHED RENAL-TRANSPLANT COMBINATIONS

Background. The aim of the present study was to analyze the effect of HLA-DRB1 mismatches on graft function and graft survival in 92 patien ts who received serologically HLA-DR split antigen-matched cadaveric r enal transplants. Methods. The polymorphic second exon of the HLA-DRB1 alleles was typed using the sequence-specific oligonucleotides techni que. Results. The results show that in 26 of the 92 analyzed combinati ons, one or more HLA-DRB1 mismatches were found (28%). The analysis o f the occurrence of treatable rejection episodes during the first 3 mo nths after transplantation demonstrated a significantly higher inciden ce of rejection episodes in the HLA-DRB1-mismatched group: 18 of 26 ( 69%) in the HLA-DRB1-mismatched group against 23 of 66 (35%) in the H LA-DRB1-matched group (P-uncorr=0.0033). However, no effect of HLA-DR B1 mismatches on graft survival was found, although in general graft survival in the whole patient group was negatively influenced by the o ccurrence of rejection episodes during the first 3 months after transp lantation (Puncorr=0.0008). In contrast, in the HLA-DR4-matched donor- recipient combinations (n=28), the effect of mismatching for the HLA-D RB104 alleles seemed to have a pronounced effect not only on the occu rrence of rejection episodes but also in the form of diminished graft survival. Conclusions. Thus, this study indicates that the existence o f HLA-DRB1 allele mismatches in renal transplant recipients, matched for the serologically defined HLA-DR split antigens, is not harmful fo r the transplant. The exception is the HLA-DRB104 mismatch, which see ms to be deleterious for the grafted organ.