title: Phenotypic and functional characteristics of active suppressor cells against IFN-gamma production in PHA-stimulated cord blood lymphocytes.
abstract: Cord blood mononuclear cells (MNC) were defective in their ability to produce interferon-gamma (IFN-gamma) on stimulation with phytohemagglutinin (PHA) or recombinant interleukin 2, whereas cord MNC could induce comparable amounts of IFN-gamma with adult controls on stimulation with a streptococcal preparation, OK-432. Moreover, irradiation of cord MNC with 1,500 rad before PHA stimulation could restore the IFN-gamma production. Kinetic studies indicated that such augmentation of IFN-gamma production by irradiation was evident when cord MNC were irradiated before or by 12 hr of PHA-stimulated culture. But irradiation after 18 hr or more of PHA stimulation did not exert any significant augmentation on IFN-gamma production by cord MNC. It seemed most likely that the ability of IFN-gamma production is already mature at birth, but radiosensitive suppressor effectors on IFN-gamma production are activated within cord MNC at an early stage of PHA stimulation, resulting in poor IFN-gamma production by cord MNC. PHA-induced IFN-gamma production by OKT3+, OKT4+, and OKT8- cord cells were markedly enhanced by irradiation with 1,500 rad before the culture. Coculture experiments disclosed that cord OKT4+ cells, but not OKT4- cells, when prestimulated with PHA for 24 hr, exerted active suppression on PHA-induced IFN-gamma production by adult MNC in a dose-dependent manner. These results suggested that radiosensitive suppressor effectors on IFN-gamma production were induced within the OKT4+ T cell subset of cord MNC on PHA stimulation.
mesh_terms: D000945:Antigens, Differentiation, T-Lymphocyte; D000954:Antigens, Surface / Q000032:analysis; D002478:Cells, Cultured; D005312:Fetal Blood / Q000166:cytology* / Q000276:immunology; D006801:Humans; D007108:Immune Tolerance / Q000528:radiation effects; D007371:Interferon-gamma / Q000096:biosynthesis*; D007376:Interleukin-2 / Q000494:pharmacology; D010835:Phytohemagglutinins / Q000276:immunology; D010844:Picibanil / Q000276:immunology; D013601:T-Lymphocytes / Q000145:classification; D050378:T-Lymphocytes, Regulatory / Q000276:immunology* / Q000528:radiation effects; D013997:Time Factors
chemical_list: D000945:Antigens, Differentiation, T-Lymphocyte; D000954:Antigens, Surface; D007376:Interleukin-2; D010835:Phytohemagglutinins; D010844:Picibanil; D007371:Interferon-gamma