[Comparative action of the low-molecular fractions from thymus and cerebral cortex polypeptides on the immune response in mice].

Rabbit antisera against low-molecular weight polypeptides from the thymus (thymosin and thymarin), brain cortex (cortexin) and white matter of the calf brain were cross absorbed with these polypeptides and tested in the complement fixation test with the above preparations. In addition they were also tested in the complement-dependent cytotoxicity test with thymocytes and bone marrow cells. Thymosin, thymarin and cortexin were shown to be antigenously similar but to differ in antigenous structure from the polypeptide of brain white matter. The biological effect of the polypeptides from the thymus and brain cortex is related to the thymus-dependent lymphocyte population rather than to B cells. Cross absorption has revealed that antisera against the polypeptides from the thymus and brain cortex contain antyibody both against common antigens and antigens specific only for the appropriate preparation. The antigenous set of thymarin responds better to thymic antigens than cortexin.