Molecular studies of a rare DR2/LD-5a/DQw3 HLA class II haplotype: multiple genetic mechanisms in the generation of polymorphic HLA class II genes

摘要: A cDNA library was constructed from a homozygous B lymphoblastoid cell line (REM) obtained an individual of long isolated American Indian tribe, the Warao. The REM expresses serologically defined determinants, DR2 and DQw3, T lymphocyte-defined (Dw/LD) specificity, LD-5a. cells can recognize differences between FJO (a DR2/DQw1 that Dw specificity MN2) for both DR DQ molecules. cNDA clones encoding polymorphic beta 1-, 2-, beta-, alpha-chains were sequenced compared with other gene sequences. 1-sequence is identical to FJO; 2-sequence also except one amino acid difference at position 67 in first domain (Leu REM, Phe FJO) due single point mutation. beta-sequence DR4/DQw3 haplotype; alpha different haplotype DR3/DQw2 Raji DR5/DQw3 deduced sequence. Taken together, these findings suggest that: 1) (position 67) third hypervariable region 2-chain apparently sufficient stimulating responses; 2) DQw3 serologic may be mainly by beta-rather than alpha-chain; 3) multiple genetic events have probably occurred generate rarely found (DR2/LD-5a/DQw3) haplotype.