Sequence analysis of HLA-DR4B1 subtypes: additional first domain variability is detected by oligonucleotide hybridization and nucleotide sequencing.

The stimulating capacity of HLA-DR4 variants in mixed leukocyte culture correlates with variation in the polymorphic regions of the first domains of their DR beta 1 chains. Variability between amino acids 67 and 86 appears largely to determine HLA-DR4,Dw type. We have used a combination of a DR4B1-specific primer set in the polymerase chain reaction and specific oligonucleotide probes to examine DR4,Dw-associated nucleotide polymorphisms. Phenotype and gene frequencies are reported among 44 normal DR4 Caucasoids. Oligonucleotide probes were selected which enabled definition of Dw4-, w14-, w10-, w13-, and w15-associated sequences. Unexpectedly, several subjects were positive for Dw15 sequences which are usually characteristic of Oriental populations. Dw15 assignment was confirmed by nucleotide sequencing of DR4B1 polymerase chain reaction products. A pair of oligonucleotides informative for the glycine or valine dimorphism at position 86 was used to identify two novel DR4B1 alleles, designated 13.2 and 14.2. Nucleotide sequencing shows that these represent recombinants between third hypervariable regions associated with Dw13 and Dw14 and a codon for glycine at position 86 which is usually found associated with Dw4 and Dw15 sequences.