The impact of HLA-DR compatibility on cadaver kidney graft survival in a prospective study with special emphasis on the quality of typing

No impact of cross-reactive group human leucocyte antigen class I matching on long-term kidney graft survival

The aim was to elucidate the effect of matching for the broad human leucocyte antigen (HLA)-A and -B cross-reactive groups (CREGs) of major histocompatibility complex (MHC) class I on long-term kidney graft survival.

MATERIAL AND METHODS

1304 patients transplanted at Rigshospitalet between 1968 and 1999 with a cadaver kidney and followed until 2000. The definition of CREGs based on amino acid residues was according to United Network for Organ Sharing (UNOS) (1996). Graft-survival analyses (Kaplan Meier) were performed for all cases and for cases censored for death with functioning grafts.

RESULTS

Univariate analysis showed no effect of any specific donor or recipient CREG on graft survival. Contrary to some reports in the literature, the absolute and relative number of CREG shares and of CREG mismatches had no effect on graft survival even when censored for graft loss because of death. However, graft survival was dependent on DR shares (P < 0.05), indicating that matching for MHC class II seems to be more important than that for the broad MHC class I phenotype represented by CREG.

Discrepancies in serological tissue typing revealed by DNA techniques

DNA techniques were applied to typing a population of renal patients in order to assess the number of discrepancies between this technique and the serological technique. Five patients had been given an incorrect type by serology, and in 22 instances allogenotypes were found where previously there had been a serological blank. DNA typing was also able to determine allogenotypic subtypes that correlated with DR antigens difficult to split by serology and to determine allogenotypic subtypes correlating with DR antigens not known to have a split by serology. Whereas DNA typing provided a result first time of testing on all but 3 patients, the average number of serological testings for each patient was 1.9.

An eight-year study of HLA typing proficiency in Eurotransplant

The main purpose of Eurotransplant, an international organ exchange organisation, is to maximize the survival time of transplanted organs through tissue typing and matching. Regular proficiency testings are necessary to assess the reproducibility and the reliability of the HLA typings performed by the individual typing centres. Two different protocols have been used: 1) since 1978, 35 samples of blood and donor spleen were used for cell exchanges (CE) and typed by all participating laboratories; 2) since 1977 samples of donor spleen have been shipped to the reference laboratory in Leiden for retyping (RD) resulting in over 2600 comparable HLA typings. The discrepancy rates of the HLA-A, B, C and DR specificities were analysed over the years. A large number of discrepancies was due to false negative assignments which led to assumed homozygosity at one or more HLA-loci. The recognition of HLA-DR has improved dramatically but with much variation per DR specificity. The concordancy rates for HLA-AB + DR have improved from 40% in 1981 to 91% for CE and 80% for RD typings in 1984. The reproducibility of DR typings in individual laboratories also has improved greatly but there is still considerable variation between the different laboratories.