Haematologia 13. (1980)
1980 / 1-4. szám - Immunology - Astaldi, A.: Thymocyte maturation induced by a thymus-dependent serum factor
Haematologia 13 (1 — 4), pp. 203 — 211 (1980) Thymocyte Maturation Induced by a Thymus-Dependent Serum Factor A. Astaldi Central Laboratory of the Netherlands Red Cross Blood Transfusion Service and Laboratory for Experimental and Clinical Immunology of the University of Amsterdam, Amsterdam, The Netherlands (Received June 11, 1979) By means of direct measurement of intracellular cyclic AMP in thymocytes in vitro we demonstrated the existence in human serum of a thymus-dependent factor (SF). This activity of SF appeared to be due to a very low M.W. (< 500) peptide distinct from other circulating thymic peptides. SF was found to act selectively on immunologically immature, hydrocortisone (HC)-sensitive peanut lectin-agglutinating thymocytes. In a period of 240 min SF sequentially induces in thymocyte synthesis of cyclic AMP, protein synthesis and synthesis of phosphorylated non-histone chromatin proteins of high molecular weight. Because SF does not induce a change in DNA synthesis, it seems likely that the events induced by SF are associated with a process requiring DNA translation, but not DNA replication. The biochemical events induced by SF are accompanied by the acquisition of immunological maturation by thymocytes. This has been shown by the acquisition of FfC resistance, by the expression of FC receptors for IgM, by the decrease of terminal transferase activity and by the induction of the capacity to elicit a graft-versus-host reaction. We conclude that, most likely, SF acts on immature thymocytes inducing a part of them to acquire some properties of mature T cells. I am not surprised at all that you could write such a grant application, I am surprised to see that you obtained the grant. J. J. ran Loghem Introduction The development of T cells into mature immunocompetent cells is probably at least partially under the influence of factors secreted by the thymus. This was suggested by the findings (a) that the immunocompetent cells in thymectomized mice, grafted with a thymus, are of host origin [ 1 ] ; (b) that immunological reconstitution of thymectomized mice is achieved by grafting a thymus enclosed in a diffusion chamber [2]; (c) that several factors, acting on T-cell maturation, have been found in thymic extracts, in peripheral blood and in supernatants of thymic epithelial cultures (for review, see ref. 3). Stutman et al. [4] proposed that target cells for thymic factors have received some form of thymic influence, probably through thymus traffic, and termed them Haematologia 13, 1980