thymosin-beta(4) and Acquired-Immunodeficiency-Syndrome

The epithelial cells of the thymus synthesize at least 30 different polypeptides: the thymic hormones. The structure of 4 of them is well known. They are named thymosin alpha 1, thymopoietin, thymulin and thymic humoral factor. Biological functions and secretion regulation of thymic hormones are described as well as the interactions between brain, thymus and endocrine glands. Blood levels and clinical usefulness of thymic hormones are reviewed in different congenital or acquired immunodeficient states and in autoimmune diseases.

Topics: Acquired Immunodeficiency Syndrome; Autoimmune Diseases; Humans; Immunologic Deficiency Syndromes; Peptide Fragments; Thymalfasin; Thymic Factor, Circulating; Thymopentin; Thymopoietins; Thymosin; Thymus Extracts; Thymus Hormones

Thymosin alpha 1 and thymosin beta 4 were first isolated from thymosin fr. 5 and have demonstrated biological activities on the immune system. They are chemically distinct and differ in their immunological activity profiles. The levels of thymosin alpha 1 and thymosin beta 4 were assessed by radioimmunoassay in the same serum samples. Normal thymosin alpha 1 levels were 670 +/- 163 pg/ml for males and 652 +/- 162 pg/ml for females. Normal thymosin beta 4 levels were 974 +/- 400 ng/ml for males and 889 +/- 345 ng/ml for females. No correlation between the levels of the peptides in serum from normal donors was observed. Although many samples of serum from neonates (cord blood), homosexuals and AIDS patients had elevated levels of one or both peptides, no correlation between the two peptides was found. Of potential significance is the observation that while thymosin alpha 1 and beta 4 are elevated in many individuals with AIDS (57 and 48% respectively), the individuals with AIDS related immune dysfunctions had predominantly elevated thymosin alpha 1 (54 vs 15%). These studies suggest that serum levels of the two peptides are modulated separately and that both are of potential value in defining the risk of individuals for developing AIDS.

Topics: Acquired Immunodeficiency Syndrome; Homosexuality; Humans; Male; Radioimmunoassay; Risk; Thymalfasin; Thymosin