title: Zinc and immunity.
abstract: The ubiquitous trace metal zinc has been discovered since a long time as an intrinsic element in all biological systems. However, its role other than structural or catalytic in enzymes is poorly defined. Zinc plays a determinative role both in primary and secondary T lymphocyte production. Experimental data support the notion that during intrathymic maturation, non-autoreactive, immunocompetent T cell clones are selected from the excess of immature thymocytes as a result of expansion of bone marrow derived prothymocytes in response to pleiotropically acting alarmon (s) and a subsequent escape via the thymic stroma cells from nucleotide-mediated "biochemical suicide". The activity of alarmon (Ap4A), nucleotide metabolizing enzymes (TdT, DNA polymerase, thymidine kinase, 5'-nucleotidase) and some of the soluble stromal cell products (FTS) require constitutive zinc. In the peripheral lymphoid organs the magnitude and duration of antigen induced, T cell mediated immunoreactions are regulated by T-cell growth factor (IL-2). Using receptor specific monoclonal antibody probes, it has been established recently that the intracellular role of IL-2 is probably to induce the phenotypic expression of high affinity transferrin receptors, known to be the main zinc transporter system in T-lymphocytes. The coordinative role of zinc in T lymphocyte development via the inducible metallothionein system is emphasized. Some clinical aspects of zinc metabolism are discussed.
mesh_terms: D000818:Animals; D002454:Cell Differentiation; D002455:Cell Division; D004247:DNA / Q000378:metabolism; D006801:Humans; D007109:Immunity; D008667:Metalloproteins / Q000502:physiology; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology; D050378:T-Lymphocytes, Regulatory / Q000378:metabolism; D015032:Zinc / Q000172:deficiency / Q000378:metabolism / Q000502:physiology*
chemical_list: D008667:Metalloproteins; D004247:DNA; D015032:Zinc