title: Evidence that thymocytes require at least two distinct signals to proliferate.
abstract: Optimal receptivity of thymocytes to the mitogenic stimulus in macrophage culture fluid (MCF) is limited to the time in culture when these cells are spontaneously proliferating. By providing a brief, nonmitogenic lectin pulse, nonproliferating cells can be "activated" and their ability to respond to MCF totally restored. This procedure provides a model system for evaluating thymocyte proliferation and, in particular, the mechanism of action of MCF.
mesh_terms: D000818:Animals; D002453:Cell Cycle; D002478:Cells, Cultured; D003208:Concanavalin A / Q000494:pharmacology; D037102:Lectins / Q000494:pharmacology; D008213:Lymphocyte Activation; D008264:Macrophages / Q000276:immunology; D051379:Mice; D008805:Mice, Inbred A; D010835:Phytohemagglutinins / Q000494:pharmacology; D013601:T-Lymphocytes / Q000276:immunology*; D013997:Time Factors
chemical_list: D037102:Lectins; D010835:Phytohemagglutinins; D003208:Concanavalin A