Impaired binding of a DQ2 and DQ8-binding HSV VP16 peptide to a DQA1*0501/DQB1*0302 trans class II heterodimer

DQ alpha and DQ beta trans heterodimeric HLA-DQ molecules form in individua ls heterozygous for the DQ2 and DQ8 specificities. Unique functions and dis ease associations have been postulated for such trans-dimers, which may be different from cis-encoded DQ molecules encoded by the corresponding haplot ypes We analyzed the ability of the trans-dimer encoded by HLA-DQA1*0501/DQ B1*0302 to bind a peptide antigen which interacts with DQ Medicine ill, mol ecules encoded by both parental haplotypes. Markedly impaired binding was o bserved, consistent with both the use oi different anchor residues and with changes in levels of DQ cis-dimer availability fur peptide binding interac tions.