[Isolation and evaluation of the specificity of an antiserum to the thymic polypeptide factor].

The specificity of antisera, obtained by the immunization of rabbits with the conjugated antigenic preparations of the thymic factor, have been evaluated by the method of immunochemical analysis. To carry out the comparative study, polypeptides isolated from the pineal body, cortex and white matter of the brain, Thy-1 antigen from the cerebral cortex and insulin have been used. The polypeptides of the thymus and the brain have been found to differ in their amino acid composition and molecular weight. The thymic factor possesses specific antigenic determinants which are absent in the tested preparations of cerebral polypeptides and insulin. The rabbit antisera obtained in this investigation are highly specific and can be used for the immunochemical determination of the thymic factor in the blood and other biological fluids.