title: Limiting dilution analysis of alloantigen-reactive T lymphocytes. IV. High frequency of cytolytic T lymphocyte precursor cells in MLC blasts separated by velocity sedimentation.
abstract: A sensitive limiting dilution microculture system was used to obtain minimal estimates of the frequency of cytolytic T lymphocyte precursor cells (CTL-P) directed against DBA/2 alloantigens, after priming of spleen cells in unidirectional mixed leukocyte cultures (MLC, C57BL/6 anti-DBA/2). The mean CTL-P frequency in day 4 to 5 MLC populations was found to be approximately 50- to 100-fold greater than the frequency in normal spleen, and up to 25% of the cells present in such MLC could be identified operationally as CTL-P. Even higher frequencies (up to 50%) of CTL-P were obtained in a population of large-sized cells separated from day 4 MLC by velocity sedimentation. Furthermore, since a strikingly quantitative correlation was observed between CTL activity and CTL-P frequency in such separated MLC populations, it is likely that mature CTL in MLC are not end cells, but can further proliferate and thus behave operationally as CTL-P.
mesh_terms: D000818:Animals; D002469:Cell Separation; D002478:Cells, Cultured; D002999:Clone Cells / Q000276:immunology; D003602:Cytotoxicity, Immunologic; D007519:Isoantigens; D007959:Lymphocyte Culture Test, Mixed; D051379:Mice; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D013601:T-Lymphocytes / Q000276:immunology* / Q000528:radiation effects; D013997:Time Factors
chemical_list: D007519:Isoantigens