Nature 268, 57 - 58 (07 July 1977); doi:10.1038/268057a0

An anterior pituitary factor stimulates thymidine incorporation in isolated thymocytes

R. K. SAXENA & G. P. TALWAR

Department of Biochemistry, All India Institute of Medical Sciences, New Delhi−110016, India

A POSSIBLE tropic role of pituitary on thymus has been suggested by several studies. Hypophysectomy causes an atrophy of the gland¹⁻⁴ and thymus is poorly developed in Snellbagg genetically dwarf mice with hypopituitary function⁵. A diminution of thymus size and a reduction in immunological responses to T cell-dependent antigens is also seen after administration of anti-hypophyseal serum⁶. The pituitary may contain several active principles affecting directly or indirectly the thymus functions. Of these, growth hormone has been shown to have a promoting effect on metabolic activities of the thymus and on immune responses involving the participation of thymus-derived T cells^4,7,8. Thyrotropin, via the thyroid hormones, also exercises a thymotropic action⁹. ACTH, via corticosteroids, causes the transient diminution of the gland¹⁰. We report here the presence in pituitaries of a previously unknown small molecular weight peptide(s) which stimulates markedly the incorporation of tritiated thymidine into DNA in isolated thymocytes.

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