Abstract: | Experiments on CBA mice showed that the gray matter homogenate of the syngeneic brain contained components reconstituting the T-cell population in the spleen of thymectomized animals and possessing a stimulating effect on the immune response to sheep red blood cells. The white matter homogenate was much less active, it is not excluded that the trace activity is due to the gray matter admixture in the preparation. Syngeneic muscle tissue homogenate possessed no biological activity. |