DQ β sequences in HLA-DR4 haplotypes

A cDNA clone encoding the entire mature DQ β chain was isolated and sequenced from the DR4-Dw14 homozygous cell line, LS40. The sequence was compared with published DQ β sequences from cells expressing DR4-DQw3, and found to be identical. The lack of DQ β sequence polymorphism within this serotype (to date, DQ β sequences have been derived from five cell lines comprising three Dw subtypes) adds to the data that suggest a recent evolutionary divergence of Dw subtypes within DR4-DQw3.