Exacerbation of mixed connective tissue disease during Salmonella gastroenteritis--serial immunological findings.

A patient with mixed connective tissue disease is described who developed fever and polyserositis after the onset of Salmonella gastroenteritis. Antiribonucleoprotein antibodies, serum complement, and circulating immune complexes were studied quantitatively throughout the course of her illness. If the Salmonella infection were responsible for the exacerbation of mixed connective tissue disease, as the sequence of events suggests, the mechanism appeared to involve deposition of previously circulating immune complexes in affected tissues.