Autoimmunity to La (SS-B) in vitro is related to HLA-DR3 in healthy subjects

In patients with Sjögren's syndrome 50-90% of those who have anti-La (SS-B) in their serum are HLA-DR3 positive. To investigate the relation between DR3 and anti-La antibody production 18 healthy subjects were divided into nine pairs, each matched for age and sex, containing one DR3 positive individual and one with a different DR type. Peripheral blood mononuclear cells from each pair were cultured with varying doses of pokeweed mitogen and supernatants from nine day cultures assayed for antibodies to La, nRNP/Sm, and DNA by enzyme linked immunosorbent assay (ELISA) using purified antigens. In each case peak anti-La secretion was greater in the DR3 positive subject than in the matched DR3 negative individual; in contrast, there was no consistent difference in levels of anti-DNA or anti-nRNP/Sm secretion. This specificity of enhanced autoantibody response in healthy individuals after polyclonal activation suggests that anti-La production may be under the control of genes linked to DR3.