title: Immunochemical studies on thymosin: radioimmunoassay of thymosin alpha 1.
abstract: A sensitive and specific radioimmunoassay (RIA) has been developed to measure thymosin alpha 1 in human blood and tissue extracts. Thymosin alpha 1, originally isolated from bovine thymosin fraction 5, has an identical primary structure in bovine and human species. Antiserum to synthetic thymosin alpha 1 was prepared in rabbits. A synthetic analogue, N-Ac-(Tyr1)thymosin alpha 1 was radioiodinated by utilizing Na125I and soluble lactoperoxidase. The RIA is capable of detecting as small an amount as 40 pg thymosin alpha 1 in serum/plasma and does not significantly cross-react with other putative thymic hormones or other purified blood proteins that have been assayed. Proteolytic degradation of thymosin alpha 1 does not occur during the collection, storage, or assay of serum or plasma. The concentration of thymosin alpha 1 in the blood is highest in utero, decreases sharply after birth, and appears to remain fairly constant during the first 15 yr of life. Maternal blood levels of thymosin alpha 1 appear to be above normal during pregnancy.
mesh_terms: D000042:Absorption; D000818:Animals; D000918:Antibody Specificity; D002850:Chromatography, Gel; D004306:Dose-Response Relationship, Immunologic; D006801:Humans; D007106:Immune Sera / Q000494:pharmacology; D007457:Iodine Radioisotopes; D007525:Isoelectric Focusing; D011817:Rabbits; D011863:Radioimmunoassay; D000077596:Thymalfasin; D013947:Thymosin / Q000031:analogs & derivatives / Q000032:analysis* / Q000276:immunology / Q000302:isolation & purification; D013949:Thymus Extracts / Q000494:pharmacology; D013951:Thymus Hormones / Q000032:analysis*
chemical_list: D007106:Immune Sera; D007457:Iodine Radioisotopes; D013949:Thymus Extracts; D013951:Thymus Hormones; D013947:Thymosin; D000077596:Thymalfasin