title: A quantitative analysis of antigen-presenting cell function: activated B cells stimulate naive CD4 T cells but are inferior to dendritic cells in providing costimulation.
abstract: Ligation of CD28 on CD4 Th1 clones and freshly isolated mixtures of naive and memory CD4 T cells triggered their T cell receptors (TCR) is sufficient to induce the costimulatory signals necessary for interleukin 2 (IL-2) production by these cells. CTLA-4-reactive ligands expressed on antigen-presenting cells (APC) are critical in providing costimulatory signals to these T cell populations. We demonstrate that these activation characteristics apply equally to purified naive CD4 T cells. Because B cell blasts express CTLA-4-reactive ligands and high levels of adhesion and major histocompatibility complex class II molecules, they would be expected to engage both the TCR and CD28 and consequently stimulate IL-2 production by naive CD4 T cells. Using purified populations of cells in limiting dilution cultures, we have carried out a quantitative analysis of the interaction between naive CD4 T cells and either activated B or dendritic cells. We demonstrate that B cell blasts stimulate a high frequency of naive CD4 T cells. Slight differences in TCR signaling efficiency between the two APC types were observed. Even at optimal peptide concentrations, however, the amount of IL-2 made by individual T cells was fourfold lower in response to B cell blasts than to dendritic cells. This relative deficiency of activated B cells was due to their inability to optimally costimulate naive CD4 T cells.
authors.affiliation: Laboratory of Cellular and Molecular Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892.
authors.forename: D J
authors.initials: DJ
authors.lastname: Cassell
authors.forename: R H
authors.initials: RH
authors.lastname: Schwartz
mesh_terms: D000069594:Abatacept; D000818:Animals; D000938:Antigen-Presenting Cells / Q000502:physiology*; D015703:Antigens, CD; D000943:Antigens, Differentiation / Q000378:metabolism; D001402:B-Lymphocytes / Q000502:physiology*; D018106:CD28 Antigens / Q000502:physiology; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D060908:CTLA-4 Antigen; D002352:Carrier Proteins / Q000032:analysis; D003713:Dendritic Cells / Q000502:physiology*; D018960:Hyaluronan Receptors; D018796:Immunoconjugates; D007376:Interleukin-2 / Q000096:biosynthesis; D008213:Lymphocyte Activation; D051379:Mice; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D011956:Receptors, Cell Surface / Q000032:analysis; D016201:Receptors, Lymphocyte Homing / Q000032:analysis
chemical_list: D015703:Antigens, CD; D000943:Antigens, Differentiation; D018106:CD28 Antigens; D060908:CTLA-4 Antigen; D002352:Carrier Proteins; C556707:Ctla4 protein, mouse; D018960:Hyaluronan Receptors; D018796:Immunoconjugates; D007376:Interleukin-2; D011956:Receptors, Cell Surface; D016201:Receptors, Lymphocyte Homing; D000069594:Abatacept