A reliable and efficient high resolution typing method for HLA-C using sequence-based typing.

Serological typing of HLA-C has been poor and almost half of its alleles are serologically undetectable blanks in most populations. Therefore, DNA typing techniques have been used to identify and type for the HLA-C gene. Sequence-based typing (SBT) has proven a major typing strategy for highly polymorphic HLA genes. The technique enables direct identification of all sequence motifs without the need to continuously adjust primers. Here we describe a reliable solid-phase SBT strategy for HLA-C which can be used to distinguish all currently known HLA-C alleles without prior knowledge gained by low resolution typing. Exons 2 and 3 were amplified and sequenced and if necessary sequences of exons 1 and 5 were determined. A total of 257 individuals were typed for HLA-C using this protocol and 30 of the 42 known HLA-C alleles were detected. All heterozygous combinations found in this study were unambiguously discriminated. One hundred and forty-four individuals from the Dutch population were typed randomly. In this group Cw0701 and 0702 were the most frequently detected alleles. Of the serological Cw blank alleles Cw1203 was found to have the highest frequency (16%). From the total group 212 individuals were typed serologically and 106 were retyped with 97 selected antisera to further compare serological and molecular defined phenotypes. Discrepancies between serological typing and SBT are mainly attributable to the serologically Cw blank alleles Cw12-18. The high resolution SBT protocol described will be a valuable tool for the identification of HLA-C alleles and the determination of the role of HLA-C in marrow and organ transplantation.