Thymic hormones biologic activity

There are many natural and biological macromolecules that possess anticancer activity. Cytokines, topoisomerase inhibitors, monoclonal antibodies, thymic hormones, cell growth inhibitors, and enzymes have been used [68], They have been recently reviewed [59,69] and their detailed description is beyond the scope of this article. The main problems connected with the administration of such natural macromolecules is their short intravascular half-life, immunogenicity, and sometimes poor solubility. Their modification with synthetic macromolecules can dramatically increase their therapeutic potential as described below. 

Diets that are low in protein, zinc, selenium, vitamin Bg, and fat may collectively depress immune function. This type of diet may be associated with either a low-caloric-intake diet or low-fat, low-meat-products diet. Zinc is an essential trace element for many biological functions, including immune functions. Indeed, zinc is required for the biological activity of a thymic hormone, called thymulin in its zinc-bound form, and is important for the maturation and differentiation of T-cells. With advancing age, zinc, thymic functions, and peripheral immune efficiency show a progressive decline. Supplementing zinc in old age restores immune efficiency. 

Probably the two most perplexing and controversial issues in thymus endocrinology are the multiplicity of apparently unique thymic factors that have been described and the pleiotropic effects on precursor T cells, as well as on mature T cells, that each of the putative thymic hormones possess (cf. Stutman, 1983). Many of the biologic activities of thymic hormones can be mimicked by nonspecific agents such as endotoxin, prostaglandins, and cyclic AMP. In addition, it is not clear why multiple different thymic factors should exhibit identical effects in some of the biological assays. 

Thymomodulin. Leucotrofina. Cell-tree thymic hormone preparation extracted from calf thymus by acid hydrolysis Composed of a mixture of biologically active acidic peptides of mol wt < 10,000. Modulates the maturation of T-cells, Prepn of crude extract from calf thymus B, Bruneiti, E. Pini, US. pat. 3,657,417 (1972 to Eltem). Electrophoretic characterization C. Secchi er at.. Rip. Ear. Set. Med. Farmacol. 4, 499 (]982), C.A. 01, 21878m (]9S4). Biological activity and comparison with other thymic hormones J. J. Twomey, N, M, Kouttab. Cell. Immunol 12, 186 (1982). Purification and pharmacodynamics eidem. 

Thymosin, Cell free, lymphocytopoietic hormone and biologically active thymic factor, comprising a family of acidic, heat-stable polypeptides, that plays an important part in the development of T-cells (thymus-dependent lymphocytes) and immunological functions in animals and man. Extraction from calf thymus and partial purification A. L. Goldstein er al. Proc. Nat Acad. Scl USA 56, 1010 (1966). Purification and characterization of thymosins and isotn of one of the active components, thymosin /ruction 5 eidem, ibid. 69, 1800 (1972). Improved isoln and properties J. A. Hooper et al. Ann. N.Y. Acad. Scl 249, ]25 (1975). 

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