title: Response of human newborn lymphocytes to alloantigen: lack of evidence for suppression induction.
abstract: Between 1:120 and 1:180 of human newborn T cells proliferate in limiting dilution cultures with allogeneic lymphocytes or with Ia-bearing monocytic stimulator cells. The proliferating responder cells were derived from both the OKT 4+ and OKT 8+ subsets as determined by immunofluorescence and by thymidine uptake. Five to seven days after an exchange blood transfusion there was a slight increase in the percentage of OKT 8+ T lymphocytes in the recipient's blood. Newborn blood also contains a population of non-T cells which proliferate in the absence of allogeneic stimulator cells. In limiting dilution cultures, the frequency of these spontaneously dividing cells was 1:3125 of mononuclear cells. Our results suggest that the newborn T lymphocyte proliferative response to alloantigen is mature by the time of birth and they provide no phenotypic explanation for the previous report of mixed lymphocyte culture-induced suppression by newborn T cells. The predominance of newborn metaphases in 2-way mixed lymphocyte cultures with adult cells (on which the previous report of suppression was based) is not seen if the non-T (stimulator) cells are irradiated. These results suggest that the data previously interpreted as evidence for suppression arose through proliferation of newborn non-T cells.
mesh_terms: D000328:Adult; D005078:Exchange Transfusion, Whole Blood; D005455:Fluorescent Antibody Technique; D006801:Humans; D007231:Infant, Newborn; D007519:Isoantigens / Q000276:immunology*; D007959:Lymphocyte Culture Test, Mixed; D008214:Lymphocytes / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D050378:T-Lymphocytes, Regulatory / Q000276:immunology*; D013936:Thymidine / Q000378:metabolism
chemical_list: D007519:Isoantigens; D013936:Thymidine