The effect of Corynebacterium parvum therapy on immunoglobulin class and IgG subclass levels in cancer patients.

Detailed serological studies have been undertaken in a small group of cancer patients receiving nonspecific immunotherapy with Corynebacterium parvum (C. parvum). These patients included 4 cases of recurrent malignant melanoma, 2 of stomach cancer and 2 of recurrent breast cancer. They all received an initial i.v. infusion of 20 mg of a formol killed suspension of C. parvum followed by 2 mg (i.m.) at weekly intervals for 10-11 weeks. This protocol consistently resulted in an increase in the circulating IgG levels of all patients but had a variable effect on their IgA, IgM and IgE levels. Increases in the concentration of all 4 IgG subclasses contributed to the overall increase in IgG levels and these changes ranked IgG2 greater than IgG1 greater than IgG3 = IgG4. It also had an inconsistent effect upon the levels of alpha-macroglobulin in pregnancy but the levels of normal serum alpha2-macroglobulin were virtually unchanged. Pre-existing antibodies to C. parvum were noted in all the patients. Titres rose appreciably following C. parvum administration and remained at high, though fluctuating levels, throughout the 100-day period of observation. Absorption studies suggested that the development of antibodies to C. parvum accounted in part for the increased IgG levels noted following this form of therapy. The significance of these changes in relation to the possible anti-tumour effect of C. parvum is discussed.