Striking elevation of serum IgA, IgA-containing immune complexes, and IgA rheumatoid factor in clinically silent dermatitis herpetiformis.

We describe a patient with dermatitis herpetiformis with immunoglobulin A (IgA)-containing circulating immune complexes and IgA rheumatoid factor who presented with acute renal insufficiency; a renal biopsy specimen showed IgA nephropathy. The renal function and proteinuria spontaneously returned to normal despite markedly elevated levels of IgA-containing circulating immune complexes, IgA rheumatoid factor, and IgA antibodies to some environmental antigens. IgA1 was the predominant subclass. IgA2-containing immune complexes and IgM rheumatoid factor were not detected. Cultures of peripheral blood mononuclear cells produced increased quantities of IgA and IgA rheumatoid factor spontaneously and after pokeweed mitogen stimulation. These data indicate that renal function can improve and remain normal despite the presence of increased levels of IgA-containing circulating immune complexes and IgA rheumatoid factor.