HLA-DPB1 allele mismatches between unrelated HLA-A,B,C,DR (generic) DQA1-identical unrelated individuals with unreactive MLC

We have used a PCR-RFLP method with one generic amplification of HLA-DPB1 second exon and 6 endonucleases to differentiate the 19 HLA-DPB1 alleles and 171 heterozygous combinations. The set of primers used in our studies produced fragment sizes different from those published before (1). The HLA-DPB1 alleles in Caucasians showed a higher frequency of DPB1*0401 and DPB1*0402, when compared to a small group of Colombians who showed a higher frequency of DPB1*0402 and DPB1*0201. We found three HLA-DPB1 alleles associated with two HLA haplotypes that result from non-random association of alleles: DPB1*0401 with HLA-A26, B38, DR4, DQA1*0301 and DPB1*0101 and DPB1*0401 with HLA-A1, B8, DR3, DQA1*0501. We also report that 70% of combinations between HLA (generic A,B,C,DR) and DQA1-identical MLC-unreactive cell mixtures showed HLA-DPB1 mismatches, suggesting that HLA-DPB1 differences are not important in MLC reactivity.