Hla-DR and Dq Typing by Polymerase Chain Reaction Using Sequence-Specific Primer Mixes Reduces the Incidence of Phenotypic Homozygosity (Blanks) Over Serology1

Abstract

Because of the inherent difficulties in allele assignment with HLA-DR serological typing, in 1993 our organ procurement organization-based HLA laboratory replaced serology with the molecular method of polymerase chain reaction using sequence-specific primer mixes (PCR-SSP) to type for DR and DQ at a resolution level equivalent to that of serologically defined antigens. In this study, we compared the incidence of DR blanks, where allocative homozygosity occurred, and graft outcome during our serology epoch (1987-1993) with that of our molecular epoch (1993-1996). The incidence of DR blanks by PCR-SSP (17.0%; 138/1101) was significantly lower (P<0.005) than in the serology epoch (21.5%; 569/2647). Although DQ is not a component of the allocation algorithm, the incidence of blanks in the molecular era (21.9%; 196/895) was 46% lower (P<0.001) than in the serology epoch (40.8%; 931/2277). Graft survival in 163 cadaveric renal transplant recipients for whom molecular DR allocation occurred (patient and donor were molecularly typed) showed that PCR-SSP typing had no significant effect on 2.5-year graft survival for patients mismatched for 0 (97%), 1 (90%), or 2 (94%) HLA-DR antigens (P=0.4; log-rank). In conclusion, molecular typing lowered the rate of DR and DQ blanks, but molecular matching for HLA DR and DQ did not influence graft outcome at 2.5 years.

IgM antibodies identified by a DTT‐ameliorated positive crossmatch do not influence renal graft outcome but the strength of the IgM lymphocytotoxicity is associated with DR phenotype*

“…HLA‐DR typing for the patients included in this study was performed by serology through March 1993, and thereafter by PCR‐SSP typing (11, 12). We have described previously in detail our method for performing DR typing by PCR‐SSP (12).…”

“…HLA‐DR typing for the patients included in this study was performed by serology through March 1993, and thereafter by PCR‐SSP typing (11, 12). We have described previously in detail our method for performing DR typing by PCR‐SSP (12). The DR typings performed for the controls used in the study (Table 2) were from 438 consecutive cadaveric donors that were DR typed in our laboratory by PCR‐SSP from March 1993 to December 1996.…”

HLA Points Assigned in Cadaveric Kidney Allocation Should Be Revisited: An Analysis of HLA Class II Molecularly Typed Patients and Donors

“…First, we found no difference in graft survival for the groups of recipients of kidneys from zero, one or two B, DR-mismatched donors compared with those who had three to four B, DR mismatches (Table 2). Our data are of particular relevance because the serologically equivalent DR antigens for each DR allele/ allele group for every patient and donor were in each case identified by a DNA testing method, PCR-SSP, a more accurate way to define DR antigens as compared with serology methods (4,5). Furthermore, kidney allocation actually occurred using those DNA obtained types.…”

“…The reason for the switch was that serology was much less accurate than DNA typing in defining DR antigens/allele groups (3,4). Before January, 1998, the method for DNA extraction and HLA-DRb1 and DQb1 amplification was previously described (5). Since that time, DNA has been extracted using the Puregene TM (Gentra Systems, Minneapolis, MN, USA) extraction kit.…”