HLA-DQ GENE COMPLEMENTATION AND OTHER HISTOCOMPATIBILITY RELATIONSHIPS IN MAN WITH THE ANTI-RO/SSA AUTOANTIBODY RESPONSE OF SYSTEMIC LUPUS-ERYTHEMATOSUS

A strong gene interaction between HLA-DQ1 and DQ2 alleles has been associated with anti-Ro/SSA autoantibodies (Harley, J.B., M. Reichlin, F.C. Arnett, E.L. Alexander, W.B. Bias, and T.T. Provost. 1986. Science [Wash. DC]. 232:1145-1147; Harley, J.B., A.S. Sestak, L.G. Willis, S.M. Fu, J.A. Hansen, and M. Reichlin. 1989. Arthritis Rheum. 32:826-836; Hamilton, R.G., J.B. Harley, W.B. Bias, M. Roebber, M. Reichlin, M.C. Hochberg, and F.C. Arnett. 1988. Arthritis Rheum. 31:496-505). To test a gene complementation mechanism for these results, restriction fragment length polymorphisms (RFLP) of the DQα and DQβ genes have been related to Ro/SSA precipitins in patients with systemic lupus erythematosus. In this study Ro/SSA precipitins are related to the simultaneous presence of a particular pair of RFLPs. A DQα RFLP associated with HLA-DQ1 and a DQβ RFLP associated with HLA-DQ2 predict that the αβ heterodimer in HLA-DQ1/DQ2 heterozygotes is most closely related to anti-Ro/SSA autoantibodies, thereby supporting a gene complementation mechanism. Beyond this effect, an RFLP associated with HLA-DQ2 and/or DR7 is also related to Ro/SSA precipitins. Multiple molecular histocompatibility mechanisms are implicated, therefore, in the production of anti-Ro/SSA autoantibodies in autoimmune disease. For anti-Ro/SSA autoantibodies in SLE, and perhaps more generally, these data show that the histocompatibility antigens are among the elements that confer autoimmune response specificity and restrict the production of particular autoantibodies among patients with systemic lupus erythematosus.