An immunological suppressor cell inactivating cytotoxic T-lymphocyte precursor cells recognizing it.

The immune system does not normally react against self components. Originally, it was postulated that self-reactive cells were somehow deleted or blocked. More recent thinking is that such cells are suppressed by regulatory networks similar to those limiting the immune response against non-self determinants. Both mechanisms may exist. I describe here a type of suppression more closely related to the first postulate. In the in vitro, one-way, mixed lymphocyte reaction (MLR), cytotoxic T-lymphocyte precursor cells (CLP) from the responder population give rise to cytotoxic T-lymphocytes (CL) capable of lysing target cells from the stimulator population. A subpopulation of cells in the spleen of athymic nude mice can, when added to such cultures, inactivate CLP capable of recognizing either the H-2 antigens or TNP modifications of the nude spleen. Regarding the nude spleen cells, activation of self-reactive cells is being prevented.