Cell-Mediated Immune Responses in Vitro

Abstract

The effects of soluble concanavalin A (Con A) or Con A-activated spleen cells on the generation of cytotoxic lymphocytes (CL) in mixed leukocyte cultures (MLC) were examined. Mitogenic concentrations of soluble Con A or small numbers of Con A-activated spleen cells substantially inhibited CL responses. The suppression was partial rather than absolute and was critically dependent upon the concentration and time of addition of soluble Con A or Con A-activated spleen cells to the MLC. Suppressive effects of Con-A activated spleen cells were mediated by T cells since suppressor cell activity was abrogated by treatment of spleen cells with anti-θ serum and complement before or after Con A activation. X irradiation of spleen cells before Con A treatment also abrogated generation of suppressor cell activity. After activation by Con A, however, the function of suppressor cells was radioresistant. Although the precise mechanism(s) of suppression is, as yet, unknown, the precursors of CL must be exposed to Con A-activated cells during the early phases of the immune response for suppression to occur. Kinetic studies revealed that suppression of CL responses was not due to a failure to initiate an immune response, but represented a response which developed initially, but subsequently aborted. The relevance of these observations to the concepts of T-cell-T-cell interaction and regulatory control of immune responses by T cells is discussed.

Experimental conditions for obtaining suppressor and helper effects on the primary in vitro immune response by lymphocytes activated by polyclonal T-cell activators.

“…Recent studies suggest that at least in one system (allotype suppression) the target for suppressor T cells is helper T cells (7,8). Also, Con A-activated cells can suppress the generation of cytotoxicity T cells (12). An important conclusion from these studies is that the experimental conditions are of major importance in determining whether suppressor effects will be obtained or not.…”

Characterisation of Cyclosporine-Induced Suppressor Cells in Murine Delayed-Type Hypersensitivity Responses

“…Others have ob served similar Ly2+ suppressor T cells in the regula tion of antibody production [23], DTH [24] and cyto toxicity [25]. Alloreactive T cells have been shown to suppress in vitro antibody responses by human lym phocytes in an antigen-specific manner, implying that alloreactive suppression is mediated by antigen-spe cific or possibly idiotype-specific T suppressor cells [26][27][28].…”

Synergistic and suppressive interactions among mouse T lymphocytes in the response to phytohemagglutinin.

“…Culture arrested on day: 2 3 4 Synergism` 2.3 (2-3) 11 5.7(3-9) 4.6(3-9) % of mitoses of ThC origin 22 (11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26) 33 35 Synergism is expressed as the ratio of the 3HTdR incorporated in the LNC-ThC mixture to that response expected from the populations alone ('/s the response of 1 x 108 LNC plus°/s of the response of 0.8 x 1(P ThC) . t 3HTdR incorporation in cultures without PHA (background) were in all cases below 1,000 cpm/culture .…”