The effect of thymosin on human T-cells from cancer patients.

The effect of thymosin on in vitro reactivity of peripheral lymphocytes to phytohemagglutinin, concanavalin A, and the formation of spontaneous E-rosettes in 54 patients with metastatic carcinomas has been studied. Thymosin increased lymphocyte responses to PHA and Con A in only 10 patients, with predominant effect seen with Con A. Twenty patients showed depressed baseline levels of E-rosettes which were increased to normal or subnormal levels after incubation with thymosin. No distinct correlation was noted between the clinical stage of the disease and the ability of lymphocytes to form E-rosettes. Although the exact mechanism by which the thymus exerts its influence on host resistance is not clearly defined, present evidence supports the concept that the thymic hormone, thymosin, may be an important addition in treatment of cancer patients by increasing cell-mediated immunity.