[Low-molecular homogeneous thymus fraction stimulating immunogenesis].

The influence of purified acetic acid thymus extract (thymarin) and its three fractions isolated by ion-exchange chromatography upon immune response to SRBC in mice was studied. Each fraction was identified as homogeneous individual material of polypeptide nature. Crude thymus extract and one of its fractions with an approximate molecular weight of 5000 exerted a strong stimulating effect on the thymus-dependent response: formation of IgM- and IgG-antibody producing cells and on the circulating antibody level.