Increased Blood Concentration of IgG Degradation Products in Prostate Cancer.

For elucidation of the mechanisms of IgG binding with human plasminogen in prostate cancer patients, we propose an original ELISA on polystyrene plates with immobilized heavy and light plasminogen chains. The level of IgG bound to plasminogen heavy chain in the serum of prostate cancer patients significantly exceeded that in healthy volunteers. IgG treated with plasmin more actively (by more than 2 times) bound plasminogen heavy chain than intact IgG. These findings indicate the involvement of lysine-binding sites of plasminogen heavy chain in the interaction with the C-terminal lysine of IgG and their fragments. ROC analysis of ELISA data showed significant differences between serum samples from patients with prostate cancer and benign prostatic hyperplasia. It is hypothesized that IgG in the tumor region undergo proteolysis and their products appear in the circulation.