HLA-B27 structure, function, and disease association.

The polymorphism of HLA-B27 alleles is located in the peptide-anchoring motif. In recent years, fundamental insights have been made into the molecular aspects of HLA-B27-restricted presentation. Subtle differences in peptide binding fine specificity are especially interesting for closely related HLA-B27 alleles that have differential association with ankylosing spondylitis. Bacterial infection has been suggested to play a role in the pathogenesis of HLA-B27-associated disease. Remarkable progress has been made in identifying peptides derived from bacteria that can be presented by HLA-B27. Despite the mechanisms proposed to explain B27-associated diseases, there are no clear correlations between peptide sequence, differential binding to B27 subtypes, and recognition by peptide-specific T cell receptors. Furthermore, new transgenic models have now been developed that we hope will allow a clearer view of the function of B27 and the mechanisms involved in the pathogenesis of spondyloarthropathies.