IGA-CONTAINING CIRCULATING IMMUNE-COMPLEXES IN DERMATITIS-HERPETIFORMIS, HENOCH-SCHONLEIN PURPURA, SYSTEMIC LUPUS-ERYTHEMATOSUS AND OTHER DISEASES

Abstract

Sera of patients with dermatitis herpetiformis [DH], Henoch-Schoenlein purpura [HSP] and systemic lupus erythematosus [SLE] were examined for Ig[immunoglobulin]A-containing immune complexes using a newly described radioimmunoassay [RIA]. The IgG Raji [human Burkitt''s lymphoma] cell RIA and the 125Clq [q fragment of complement component 1] binding assay were used to detect IgG- and IgM-containing soluble immune complexes. IgA-containing immune complexes were found in sera of 12 of 49 (24%) patients with DH, 4 of 6 (67%) patients with HSP and 7 of 10 (70%) patients with SLE. IgG- or IgM-containing immune complexes were found in 6 of 47 patients with DH, in 1 of 6 patients with HSP and in 9 of 10 patients with SLE by the 125I-Clq binding assay or the IgG Raji cell assay. The finding of soluble IgA immune complexes in a high percentage of patients with SLE and HSP suggests that they may play an important role in the pathogenesis of these diseases. Their low prevalence in patients with DH suggests that IgA-containing immune complexes may not play a major role in pathogenesis of DH.