title: Heterogeneous accessory cell requirement for human peripheral blood T lymphocyte activation by PHA into IL-2-responsive colony-forming cells.
abstract: Mitogen-driven T cell proliferation in liquid culture requires accessory cells that cooperate in interleukin 2 production. We have investigated the accessory cell requirement for human lymphocyte colony formation under PHA stimulation. Semisolid medium limits cell-to-cell contact emphasizing the role of cooperating cells both in growth factor production and in triggering events. Culturing at high T cell density demonstrates that accessory cells can be substituted for colony formation by exogenous IL-2. Culturing at low T cell density in the presence of IL-2 also demonstrates that accessory cells are required for activation of a subset of progenitors into IL-2 responsive colony-forming cells. Consequently, T colony progenitors, contained in the E-rosetting cell fraction of peripheral blood, are heterogeneous in their triggering signals: a minor subset is directly inducible by PHA, and a major subset is inducible by PHA in the presence of accessory cells. We found that monocytes and some leukemic B cells support effective accessory function in both colony growth factor production and colony progenitor sensitization.
mesh_terms: D001402:B-Lymphocytes / Q000276:immunology; D003114:Colony-Forming Units Assay; D004306:Dose-Response Relationship, Immunologic; D006412:Hematopoietic Stem Cells / Q000276:immunology*; D006801:Humans; D007376:Interleukin-2 / Q000502:physiology*; D008213:Lymphocyte Activation; D008211:Lymphocyte Cooperation; D008214:Lymphocytes / Q000276:immunology; D009000:Monocytes / Q000276:immunology; D010835:Phytohemagglutinins / Q000494:pharmacology; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology*
chemical_list: D007376:Interleukin-2; D010835:Phytohemagglutinins