Immune complexes in human melanoma: a consequence of deranged immune regulation.

Circulating immune complexes were detected in 62 individuals with malignant melanoma by precipitation with isolated human C1q and polyclonal rheumatoid factors. In 56 patients the C1q deviation assay showed low to moderate levels of complexes, with increased amounts with advancing stage of disease. Both heavy (greater than 19S) and intermediate (7S to 19S) varieties were present, and complexes containing tumor antigen-antibody or antibody-anti-antibody were identified. Complexes were found in the kidneys of one patient with malignancy and the nephrotic syndrome and in two further patients with melanoma in whom there were no clinical manifestations of nephrosis. Serial determinations in 51 patients showed slow cyclic variations in the levels of complexes and fluctuations in response to therapy. The coexistence of anti-antibodies, immune complex disease, and anergy in melanoma patients may indicate a deranged immune regulation consequent to chronic antigenic stimulation by the tumor.