Restorative effect of short term administration of thymulin on thymus-dependent antibody production in restraint-stressed mice

Thymulin is a well defined nonapeptide produced by thymic epithelial cells, and plays an important role in thymocyte differentiation. We investigated the restorative effect of thymulin on the stress-induced reduction in the production of antibodies against SRBC in mice. Antibody production in stressed mice was reduced to about 50% of that in normal mice. A 3-day period of administration of thymulin (1 ng/kg) restored antibody production to close to the normal level, whereas thymulin (1 ng−1 μg/kg) did not affect antibody production in normal mice. These results indicated that thymulin normalizes the altered thymus-dependent immune responses.