Clinical applications of complement measurements in rheumatic diseases.

There is now convincing evidence that the complement system is involved in the pathogenesis of at least some of the manifestations of human rheumatic diseases. Complement measurements in serum and/or pathologic fluids from patients with these disorders not only reflect this involvement but also may provide important clues regarding the activity and extent of the disease processes. Future studies should provide additional information concerning the usefulness of such measurements for predicting the outcome of specific therapeutic regimens, and perhaps also be the basis for the evolution of new and more rational forms of therapy.