Partial characterization of serum suppressor factors in patients with cervical squamous carcinoma

A cell-mediated cytotoxicity system was used to characterize the suppressor factors in sera from patients with invasive squamous cell carcinoma of the uterine cervix. The immunoglobulin-M fraction of the sera of 17 patients with different stages of invasive squamous cell carcinoma of the cervix, separated by Sephadex gel filtration, were tested. All showed marked cytotoxic suppressor activity, including two cases in which sera showed only mild activity. The immunoglobulin-G fraction of sera from 13 patients with invasive squamous cell carcinoma of the cervix was separated by ion exchange chromatography. The cytotoxic suppressor activity of the immunoglobulin-G fraction proved to be comparable in effect to that of the whole sera. By using increasing dilutions of IgG and IgM fractions, it could be demonstrated that IgM fraction retained its activity at 0.01 +/- 0.005 mg/ml whereas IgG fraction was devoid of activity at this concentration, suggesting that these two immunoglobulin fractions act independently. It is suggested that the cytotoxic suppressor activity in sera from patients with invasive squamous cell carcinoma of the cervix resides in the gamma globulin fraction and that both immunoglobulin-M and immunoglobulin-G of their sera manifest the cytotoxic suppressor activity independently. (Am J Reprod Immunol. 2:199-203.)