The effect of DTC on mitogen-induced proliferation of thymocytes in restrained mice. comparison with calf thymus extract

The cardinal sign of acute stress is thymic involution, which subsequently attenuates the activity of immunocompetent cells, notably T-lymphocytes, macrophages and NK cells. Sodium diethyldithiocarbamate (DTC), a low molecular weight sulphur compound, may function as a thymic hormone to induce precursor cells to become functionally mature T-lymphocytes. The studies were conducted on Balb/c mice exposed to restraint stress twice for 12 h at 24 h intervals. DTC at a dose of 20 mg/kg or calf thymus extract (TFX) at a dose of 10 mg/kg were injected i.p. four times at 24 h intervals prior to the exposure. It has been found that restraint stress markedly reduces the number of thymocytes which is concomitant with reduction in the weight of the thymus. In our study the changes sustained for 10 days of the observation. Besides, alterations in proliferative response of the thymocytes stimulated in vitro with concanavalin A (Con A) and phytohemagglutinin (PHA) were observed. The proliferative response of thymocytes to Con A was reduced 24 h after the exposure to restraint stress, but between days 4 and 7 it was found at increased levels, which decreased again on day 10. In contrast, the proliferative response of thymocytes to PHA was depressed for the entire 10 day period of the observation. It has been found that DTC and TFX administered to mice prior to restraint stress successfully counteract stress-induced immunosuppression, albeit TFX exerts stronger protective and regenerating impact on the thymus than DTC. TFX totally inhibits the suppressive effect of stress on proliferative activity of the thymocytes stimulated in vitro with Con A and PHA, stimulates restoration of thymic cells and increases the weight of the thymus. In contrast, DTC is not able to counteract the decrease in proliferative response of thymocytes to PHA.