title: Human cord blood suppressor T lymphocytes. II. Characterization of inducer of suppressor cells.
abstract: Previously, we reported an antigen nonspecific inducer of T suppressor cell factor (TisF) produced by cord blood mononuclear cells (MNC) in 48-hr, two-way mixed lymphocyte cultures (MLC). The target of this factor was a radiosensitive, T4+ (T8-) adult suppressor T cell subset. The cellular origin of this TisF was examined in the present study. IgG production by pokeweed mitogen (PWM)-stimulated adult MNC was used as an assay for TisF activity. It was found that TisF-producing cells formed rosettes with sheep erythrocytes (E+) and were independent of adherent cells (AC) in the production of TisF. They were resistant to irradiation (2500 rads) and phenotypic characterization with T cell reactive monoclonal antibodies indicated that they resided in the T8- (T4+) population. Furthermore, both TQ1- and TQ1+ cells were required for the production of TisF activity and such activity could not be reconstituted by supernatants from TQ1- MLC and TQ1+ MLC. These results indicate that the production of TisF is dependent upon interactions between radioresistant E+, T8-, TQ1- and radioresistant E+, T8-, TQ1+ cells.
mesh_terms: D000911:Antibodies, Monoclonal; D005312:Fetal Blood / Q000166:cytology / Q000276:immunology*; D006801:Humans; D007165:Immunosuppression Therapy; D066298:In Vitro Techniques; D007231:Infant, Newborn; D007959:Lymphocyte Culture Test, Mixed; D010641:Phenotype; D011836:Radiation Tolerance; D013601:T-Lymphocytes / Q000145:classification / Q000276:immunology / Q000528:radiation effects; D050378:T-Lymphocytes, Regulatory / Q000276:immunology*
chemical_list: D000911:Antibodies, Monoclonal