Distinct effects of thymic epithelial culture supernatants on T cell properties of mouse thymocytes separated by the use of peanut agglutinin
Kruisbeek, A.M.; Astaldi, G.C.
Journal of Immunology 123(3): 984-991
1979
ISSN/ISBN: 0022-1767 PMID: 313959 Document Number: 147085
Supernatants from thymic epithelial cultures (TES), a putative analog of thymic humoral function, induce strong cytolytic T [thymus-derived] lymphocyte (CTL) responses when added to primary mixed lymphocyte cultures (MLC) with thymocytes as responder cells. No enhancing effects of TES are observed with spleen cells or hydrocortisone-resistant thymocytes. These effects of TES on functional T cell parameters are accompanied by a reduction in part of the thymocytes in Thy 1 antigen density and sensitivity to hydrocortisone (HC). Immunocompetent T cells are found only among the HC-resistant thymocytes expressing a low Thy-1 antigen density. These findings suggest a TES-induced maturation process of thymocytes. The enhancing effects of TES on T cell proliferative capacity and T cell killer function of thymocytes may be due to an effect on previously unresponsive immature T cells or merely to extra stimulation of already responsive cells. The peanut agglutinin (PNA)-agglutination technique as a reversible probe showed that TES affects the T cell-proliferative and CTL responses of the PNA-agglutinating thymocytes only. TES may induce maturation of immature thymocytes, inasmuch as the PNA-agglutinating cells represent the immunoincompetent cells which are rich in Thy 1 and poor in H-2 antigens and HC-sensitive. The PNA-non-agglutinating thymocytes exhibited high reactivity in all the functional assays investigated (like HC-resistant thymocytes) and this could not be further enhanced by TES. Supernatants from non-thymic epithelial cultures or from thymic lymphocyte cultures exhibit no effects on any of the above-mentioned parameters. TES may represent a relevant in vitro model for studying thymic humoral function.