SSOP TYPING OF THE 10TH INTERNATIONAL HISTOCOMPATIBILITY WORKSHOP REFERENCE CELL-LINES FOR HLA-C ALLELES

HLA-C gene products are the most poorly understood of the HLA class I molecules because they express at low level on the cell surface compar ed to HLA-A and -B. However, recent evidence shows that HLAC molecules are functionally competent in eliciting T-cell responses and in contr olling NK-cell recognition. Approximately 20 to 50% of HLA-C alleles t ype ''blank'' in most populations. To provide a better definition of t he HLA-C alleles, we analyzed 98 extensively characterized B-cell line s from the 10th International Histocompatibility Workshop. Selective H LA-C-specific DNA amplification of exons 2 and 3 from DNA prepared fro m the cell panel was achieved with the use of two sets of locus-specif ic primers. We used 64 sequence-specific oligonucleotide probes (SSOPs ) complementary to variable sites in exons 2 and 3 to generate hybridi zation patterns. Twenty-five alleles were found among these patterns, including seven new alleles in the homozygous cell lines and seven pot ential new alleles in heterozygous cell lines. Differences between the new alleles and known alleles were generally small. Five major groups were identified in the Cw ''blank'' cells by the SSOP patterns. In ad dition, linkage between HLA-B specificities and HLA-C alleles was simi lar to previous observations. The present study demonstrated that SSOP typing was effective in identifying new alleles in homozygous typing cells but not in the heterozygous cells. Also, DNA typing can facilita te the identification of all HLA-C alleles, including those that serol ogically type as blanks. The HLA-C locus may be more polymorphic than was previously recognized.