Abstract: The HLA class II genotypes were determined in the B‐lymphoblastoid cell lines selected for the Tenth International Histocompatibility Workshop. The HLA class II genes were determined by the PCR‐SSOP method using the reagents provided by the Eleventh Histocompatibility Workshop. Additional studies have been performed for further characterization of HLA class II polymorphism on these cell lines. It is observed that several cell lines have HLA class II haplotypes with the same DRB1, DQA1 and DQB1 alleles on both haplotypes but different alleles at the other class II loci, confirming that these cell lines are not truly HLA class II‐homozygous. Other cell lines carried HLA class II haplotypes which were only different at the DRB1 gene. These results suggest double recombination events or gene conversion‐like events in generation of HLA DR, DQ haplotypes. These cell lines provide an important tool as references for HLA DNA typing.
