Article: article from journal or magazin.
Subpopulations of CD4- CD8- murine thymocytes: differences in proliferation rate in vivo and proliferative responses in vitro.
European Journal of Immunology
Cell sorting and cytotoxic depletion procedures were used to subdivide the population of CD4- CD8- ("double-negative") thymocytes from adult CBA mice on the basis of expression of Ly-1, HSA (the "heat-stable antigen" M1/69 or B2A2), Pgp-1 glycoprotein, Thy-1, MEL-14 and the PC61 antigenic determinant on the IL2 receptor (IL2R). The level of dividing cells within these subsets was assessed by brief in vivo administration of [3H]-thymidine, followed by radioautography, or by flow cytometric cell cycle analysis after DNA staining. The capacity of the subsets to proliferate in culture, in response to stimulation with concanavalin A (Con A), or with phorbol myristate acetate (PMA) and the calcium ionophore ionomycin, was assessed in high cloning efficiency single-cell culture systems. In general, the proliferative response in culture was inversely related to the rate of cell division in vivo. Response of the double-negative subsets to Con A correlated with expression of the T cell antigen receptor complex; although a high cloning efficiency was obtained from the receptor-positive fractions, very few of the clones were cytotoxic. In particular, a major Ly-1+ HSA- Pgp-1+ double-negative subset, as well as minor Ly-1- HSA- Pgp-1+ subsets, contained very few cells in cycle in vivo, but showed a high cloning efficiency in both culture systems. Conversely, the other major double-negative subset, Ly-1- HSA+ Pgp-1-, included most of the cells in cycle, but showed a reduced cloning efficiency in response to PMA and ionomycin and failed to respond to Con A. The dividing cells within the Ly-1- HSA+ Pgp-1- group were strongly enriched in the IL2R- rather than in the IL2R+ subset, suggesting IL2 was not the growth factor maintaining their proliferation in vivo.
Animals, Antigens, Differentiation, T-Lymphocyte/analysis, Antigens, Ly/analysis, Antigens, Surface/analysis, Antigens, Thy-1, Cell Differentiation, Cell Division, Cell Separation, Clone Cells/classification, Clone Cells/cytology, Lymphocyte Activation, Male, Mice, Mice, Inbred CBA, Phenotype, Receptors, Immunologic/analysis, Receptors, Interleukin-2, Receptors, Lymphocyte Homing, T-Lymphocytes/classification, T-Lymphocytes/cytology, T-Lymphocytes, Cytotoxic/cytology, T-Lymphocytes, Cytotoxic/immunology
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