[Genetic conditions for the induction and realization of the action of specific T-suppressors immune to H-2 antigens].

Spleen T-cells of mice immunized intravenously with gamma-irradiated allogenic lymphoid cells at a high dose are shown to inhibit the activation of DNA synthesis in MLC. The difference in the whole H-2 complex or in either of its K, I, D regions or I-subregions is required and sufficient for induction of specific T-suppressors. The magnitude of the suppression is a sum of suppressive reactions induced separately by each of the immunizing complex components, the products of one of the H-2 regions (subregions) as shown by changing the source of stimulator cells in MLC. These components have a similar impact in the suppressor activity. Unlike the other T-cell subclasses, T-suppressors react only to serologically defined mutant antigens of the Dd allele, but do not react to the mutants of the Kb allele and do not discriminate Kb and Kba antigens. Specific suppressor T-cells recognize the I-subregion products without their linkage to the K/D region products. For elicitation of the suppression two conditions are required and sufficient: a) direct contact of immune suppressors with the corresponding antigenic determinant; b) the subregion IC identity between the suppressors and the responder cells. Intensity of suppression is reduced if F1 hybrid responder cells interact with parent suppressor cells, but is not reduced in the inverse arrangement of the experiment. Specific suppressor T-cells are presumed to differ from other subclasses of T-cells and to be similar to B-cells relatively to the nature and multiplicity of recognizable individual products of the H-complex and to narrow specialization of reactive clones.