Detection of circulating immune complexes in pathological human sera.

The results of attempts to detect circulating immune complexes in sera by two methods are described. Both rely on the binding of the first complement component (C1) to the complex for its detection. The results, using these methods, of attempts to show which patients have complexes which contain nucleic acid and hence possibly viral antigens in the complexes are discussed. The anti-complementary complexes found in some patients seem to be associated with immune-complex vascular disease.