CLARIFICATION OF HLA-B SEROLOGICALLY AMBIGUOUS TYPES BY AUTOMATED DNA-SEQUENCING

Assignment of HLA-B types can be hampered by ambiguous reactivity of t he typing sera resulting in inaccurate HLA-B assignments. In this stud y, 19 Korean samples exhibiting ambiguous serologic reactivities were characterized by DNA sequencing. Alleles identified from 7 samples wer e previously undetected in this population (B1517, B*4101, B*4701, B* 5001, and B5106) and from 9 samples were common alleles in this popul ation (B4002, B*4003, B*4006, B*1501, B*1401, B*67012, and B*5401). T hree samples were putative HLA-B homozygotes. Three major factors caus ing serologic ambiguity were identified: weak or false negative reacti vity of typing sera (52.4%); cross or false positive reactivity of the sera (38.1%); and absence of information on the reaction patterns due to the lack of appropriate sera in the typing kit (e.g. B4101 encode d molecule) or to the presence of recently characterized molecules (e. g. B5106 encoded molecule) (9.5%). Overall, sequencing was helpful in clarifying ambiguous serologic reaction patterns improving the HLA ty ping for the Korean population.