Immune complex-mediated rheumatic diseases: the evidence and the enigmas.

Clearly, many of the connective tissue disorders are intimately associated with either focal tissue evidence of immune complex deposition or markedly elevated levels of complexes during acute disease activity. In many diseases, such as systemic lupus erythematosus or rheumatoid arthritis, the immune complexes have been firmly established as basic elements in pathogenesis. In other disorders, however, the presence or measurable elevation of circulating immune complex materials may represent an epiphenomenon that reflects tissue injury secondary to the underlying inflammatory process. Much more precise definition of these problems awaits further longitudinal study.