Background: The detection, measurement and characterization of circulating immune complexes (CICs) in tumor patients has shown both good and poor correlation with progression of the disease. The origin of the antigens making up the immune complexes in the sera of the cancer patients examined is unknown. They are perhaps antigens specific to the cancer’s progress.Material/Methods: The levels and molecular weights of circulating immune complexes were estimated in the sera of 48 patients with adenocarcinoma (grades G-1, G-2, and G-3) and 21 patients with benign prostate hyperplasia (BPH) by means of the polyethylene glycol (PEG) precipitation test.Results: The results were compared with those of a group of 45 healthy blood donors. Elevated levels of CICs were observed in 66.7% of the patients with adenocarcinoma and in 38% of those with BPH. No seropositivity for CICs was observed in the control group. Increased seropositivity for CICs was observed in patients with the highness grade of adenocarcinoma: the proportion of seropositive patients in the group of patients with the G-1 phase of disease was 50%, with G-2 75%, and with G-3 71.3%. The molecular weights of the CIC proteins were determined by SDS/PAGE. The serum CICs of both BPH and prostate cancer patients consisted of proteins absent in the CICs of the sera of healthy persons.Conclusions: Determination and analysis of atypical proteins in CICs resulting from carcinogenesis may by useful in improving the diagnosis.

Keywords: Antigen-Antibody Complex - blood, Electrophoresis, Polyacrylamide Gel, Prostatic Hyperplasia - blood, Prostatic Neoplasms - blood, Prostatic Neoplasms - diagnosis, Prostatic Neoplasms - immunology, Antigen-Antibody Complex - blood, Electrophoresis, Polyacrylamide Gel, Prostatic Hyperplasia - blood, Prostatic Neoplasms - immunology