Relationship between circulating immune complexes and urinary antigens in human malignancy

Urine samples obtained from patients with histologically proved melanoma and sarcoma were analyzed for the presence of tumor‐associated antigens by complement fixation and enzyme immunoassay. Also, serum samples obtained during 24‐hour urine collection from these patients were analyzed for circulating immune complexes by the complement consumption method and by the K562 radiometric assay. Of 36 cancer patients who were positive for urinary antigen (UA) by both assays, 28 (78%) were also positive for CIC in the two assays, six (17%) were positive in one of the two CIC‐detection assays, and two (5%) were negative in both assays. Of 24 patients that were negative for CIC in both assays, ten (42%) were also negative for UA in both assays, i.e., complement fixation and enzyme immunoassay; 12 (50%) were negative by one of the two assays; and only two (8%) exhibited UA by both assays. This relationship was more striking for melanoma than sarcoma patients. In a melanoma patient whose samples were studied sequentially during his thermochemotherapy, the fluctuations in CIC and UA were parallel. These results suggest that excretion of tumor‐associated antigen into urine is not an isolated phenomenon; rather, immune complex deposition in kidneys appears to cause glomerular damage which may allow the passage of the antigens into the urine.