[The HLA system and rheumatoid arthritis].

Recent developments in molecular biology allow a more detailed description of and insight into the interaction between T-cell receptor, antigen/peptide, and MHC gene products. These advances also provide a better approach to understanding the molecular genetics of susceptibility to certain diseases. This review tries to interpret MHC structure/function relationships, using rheumatoid arthritis as a paradigm. The following aspects are of special importance: Most likely MHC class-II gene products are directly involved in the pathogenic process and are not only to be considered as "markers". Susceptibility to rheumatoid arthritis is not associated with a single serologically defined HLA-specificity (e.g., HLA-DR4). However, there is substantial evidence that shared functional epitopes on different MHC molecules (e.g., HLA-DR1 and HLA-DR4 subtypes) confer risk for rheumatoid arthritis.