DR4 related antisera pattern differences in insulin dependent diabetes mellitus and rheumatoid arthritis.

Three allosera patterns of reactivity are described which appear to define subtypes of DR4 and segregate in families with different DR4 bearing haplotypes. There appears to be a preponderance of one particular subtype (termed DR4.3) occurring in type I insulin dependent diabetes mellitus, while in rheumatoid arthritis the distribution of subtypes within DR4 individuals is similar to that seen in controls. Although we refer to DR4 subtypes the proof that these sera are detecting a determinant on the DR molecule and not a product of another locus, an allele of which is linkage disequilibrium with DR4, awaits immunochemical confirmation.