[Isolation, purification and identification of an immunomodulating polypeptide from human and calf thymus]

A comparison of human and calf thymus extracts was carried out. The thymus extracts and the fractions isolated from them differ in their physico-chemical properties, amino acid composition and biological activity. The extracts tested contain different amounts of the thymus factor, which stimulates the reactions of cellular and humoral immunity. The results obtained suggests that calf and human thymus contain only one immunomodulating factor, namely thymarin, a component of thymus extracts from various sources, in particular of thymosin. In some of its physico-chemical properties thymarin is similar to histone H1 from calf thymus, thus suggesting an essential role of this histone in the formation and differentiation of T-lymphocytes. A possibility of quantitative estimation and identification of the immunomodulating polypeptide in thymus extracts obtained by various methods is postulated.