title: Subpopulations of CD4- CD8- murine thymocytes: differences in proliferation rate in vivo and proliferative responses in vitro.
abstract: 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.
mesh_terms: D000818:Animals; D000945:Antigens, Differentiation, T-Lymphocyte / Q000032:analysis; D000950:Antigens, Ly / Q000032:analysis; D000954:Antigens, Surface / Q000032:analysis; D002454:Cell Differentiation; D002455:Cell Division; D002469:Cell Separation; D002999:Clone Cells / Q000145:classification / Q000166:cytology / Q000276:immunology; D008213:Lymphocyte Activation; D008297:Male; D051379:Mice; D008808:Mice, Inbred CBA; D010641:Phenotype; D011971:Receptors, Immunologic / Q000032:analysis; D015375:Receptors, Interleukin-2; D016201:Receptors, Lymphocyte Homing; D013601:T-Lymphocytes / Q000145:classification* / Q000166:cytology / Q000276:immunology; D013602:T-Lymphocytes, Cytotoxic / Q000166:cytology / Q000276:immunology; D018800:Thy-1 Antigens
chemical_list: D000945:Antigens, Differentiation, T-Lymphocyte; D000950:Antigens, Ly; D000954:Antigens, Surface; D011971:Receptors, Immunologic; D015375:Receptors, Interleukin-2; D016201:Receptors, Lymphocyte Homing; D018800:Thy-1 Antigens