Intrathymic injection of antigen: A potent procedure for the induction of suppressor T cells

Specific Suppressor T‐Cells Immune to Antigens of the H‐2 Complex: Receptors, Clonal Structure, Genetic Restriction and Antigenic Markers

“…This possibility is supported by T-suppressor generation in spite of the functional T-ampIifyer inactivation by cyclosporine A in murine (Gunn et al 1981) and human MLC (Hess et al 1983), as well as within culture conditions excluding CTL generation because of poor T-amphfyer function (Hodes & Hathcock 1979, Eisenthal et al 1977, Sondel et al 1977. The rapid T-suppressor generation in vivo in tissue culture is promoted by antigen administration in non-optimal amounts (Kontianen & Feldman 1976), in non-physiological form (Chin et al 1980), by non-physiological means of administration (Shimizu et al 1979) or in non-physiological conditions (within burns, for example) (Miller & Cloudy 1979). It is tempting to suggest the T-suppressor generation to be one of the most early and universal immune response which is least fastidious in the induction requirements and shows a low activation threshold especially when an antigen penetrates the lymphoid tissue in non-physiological conditions.…”

Tumor enhancing T lymphocytes in mice: Further studies on characteristics and mechanism of activity

“…Or, alternatively, the difference might simply be quantitative. A related report of interest describes generation of suppressor T cells following injection of antigen into the thymus (Shimizu et al, 1979). Contact between immature T cells and tumor either via tumor-cell penetration of the thymus (Haran-Ghera et al, 1981) or by premature release of thymocytes to the periphery , or a combination of both might thus trigger a suppressive process that could switch off the immune response against the tumor and against other antigens as well.…”

Mechanisms of Tolerance Induction by Hematopoietic Chimerism: The Immune Perspective

“…For example, nonresponsiveness induced by intrathymic antigen inoculation leading to acceptance of islet grafts has been attributed to clonal deletion mediated by direct alloantigen recognition by host APC , which is sustained by peripheral suppressor cells . The limitations of this approach in simulating central unresponsiveness have been soon recognized because transplantation of thymic fragments containing epithelium‐expressing alloantigens does not absolutely prevent rejection despite induction of suppressor cells . Inasmuch as the thymus holds the capacity to control the reactivity of newly developed thymocytes by positive and negative selection , direct inoculation into thymus is a rather unreliable mode of tolerization to alloantigens .…”

“…For example, extrathymic deletion of alloreactive T cells is mandatory to establishment of tolerance following hematopoietic cell transplantation using costimulatory blockade . Third, naturally occurring suppressor subsets originating from the thymus and operating in the periphery play a central role in induction and maintenance of tolerance .…”