Characterization of three functional sites in alpha beta 1 DR of DRw13. All three sites are potentially involved in major histocompatibility complex-peptide interaction.

An HLA-DR product encoded by the HLA-DRw13/Dw19 haplotype has been identified as the HLA class II molecule involved in antigen presentation to several influenza-specific helper T cell clones. Three different functional sites were identified on this molecule by comparing the structure of HLA-DR products of known sequences and their ability to efficiently present foreign antigen to the T cell clones. These functional sites were mapped on the recently proposed three-dimensional structure of HLA class II molecules. From their position, these sites are all potentially involved in HLA-peptide interaction and capable of affecting the binding and/or the conformation of the foreign peptide. This suggests that polymorphic residues essential in major histocompatibility complex restriction are mostly involved in peptide binding.