Thymus cells suppress the in vitro cytotoxic response against trinitrophenyl (TNP) modified syngeneic cells.

The regulatory role of adult thymocytes in the in vitro cytotoxic cell formation against TNP-coupled syngeneic spleen cells was studied. Thymocytes are known to amplify the cytoxic response of lymph node cells against allogeneic cells. This kind of synergism was not found in the response against TNP-coupled cells; on the contrary, thymocytes had a clear suppressive effect. Thymocytes inducing this suppression must be present already at the beginning of the in vitro response. Mitotically blocked (mitomycin-C treated) thymocytes but not heat killed or lysed cells were also capable to suppress anti-TNP cytotoxicity.