Immunosuppression and reconstitution with thymosin after radiation therapy

Since 1976, 102 patients with advanced squamous cell carcinoma, (82, head and neck; 20, esophagus), have been evaluated before receiving irradiation and thymosin fraction 5 therapy at the University of California, San Francisco (UCSF). Thymosin fraction 5 is a mixture of at least 20 polypeptides which has been shown to have immune enhancing capabilities in primary immunodeficiency disease and various malignancies. Immunity prior to treatment (measured by total lymphocyte count, E and EAC rosettes, lymphocyte stimulation with phytohemagglutinin (PHA) and in mixed leukocyte culture (MLC) with allogeneic cells and quantitative serum immunoglobulins) was comparable and normal in the 80 control patients and the 22 thymosin treated patients. Postirradiation significant depression (p < 0.01) was demonstrated in cellular immunity in both groups of patients with decreased T and B cell numbers and depressed PHA and MLC stimulation. To date there have been an equal number of recurrences and deaths in both groups of patients.