title: T cells undergo rapid ON/OFF but not ON/OFF/ON cycling of cytokine production in response to antigen.
abstract: Inflammatory cytokines such as IFN-gamma and TNF produced by Ag-stimulated CD4(+) and CD8(+) T cells are important in defense against microbial infection. However, production of these cytokines must be tightly regulated to prevent immunopathology. Previous studies, conducted with BALB/c mice, have suggested that 1) CD8(+) T cells maintain IFN-gamma production but transiently produce TNF in the continued presence of Ag and 2) lymphocytic choriomeningitis virus-specific and in vitro-propagated effector CD8(+) T cells could rapidly cycle IFN-gamma production ON/OFF/ON in response to Ag exposure, removal, and re-exposure. In contrast with CD8(+) T cells, our results show that Listeria monocytogenes-specific CD4(+) T cells from C57BL/6 mice rapidly initiate (ON cycling) and maintain production of both IFN-gamma and TNF in the continued presence of Ag. Upon Ag removal, production of both cytokines rapidly ceases (OFF cycling). However, if the initial stimulation was maximal, Ag-specific CD4(+) T cells were unable to reinitiate cytokine production after a second Ag exposure. Furthermore, L. monocytogenes-specific CD8(+) T cells in the same mice and lymphocytic choriomeningitis virus-specific CD8(+) T cells in BALB/c mice also underwent ON/OFF cycling, but if the initial Ag stimulus was maximal, they could not produce IFN-gamma after Ag re-exposure. As the initial Ag dose was reduced, the number of cells producing cytokine in response to the second Ag exposure exhibited a corresponding increase. However, T cells that were marked for IFN-gamma secretion during the first stimulation did not contribute cytokine production during the second stimulation. Thus, T cells are not able to undergo rapid ON/OFF/ON cytokine cycling in vitro in response to Ag.
authors.affiliation: Department of Microbiology, University of Iowa, Iowa City 52242, USA.
authors.forename: Gail A
authors.initials: GA
authors.lastname: Corbin
authors.forename: John T
authors.initials: JT
authors.lastname: Harty
mesh_terms: D000818:Animals; D000938:Antigen-Presenting Cells / Q000166:cytology / Q000276:immunology; D000941:Antigens / Q000235:genetics / Q000494:pharmacology*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology / Q000378:metabolism; D002452:Cell Count; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D018984:Epitopes, T-Lymphocyte / Q000276:immunology; D007117:Immunization, Secondary; D007156:Immunologic Memory; D007371:Interferon-gamma / Q000096:biosynthesis* / Q000378:metabolism; D008089:Listeria monocytogenes / Q000235:genetics / Q000276:immunology; D008088:Listeriosis / Q000235:genetics / Q000276:immunology; D008213:Lymphocyte Activation / Q000235:genetics; D008217:Lymphocytic choriomeningitis virus / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D009698:Nucleoproteins / Q000276:immunology; D010047:Ovalbumin / Q000235:genetics / Q000276:immunology / Q000494:pharmacology*; D010446:Peptide Fragments / Q000276:immunology; D011948:Receptors, Antigen, T-Cell / Q000502:physiology; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology* / Q000378:metabolism*; D050378:T-Lymphocytes, Regulatory / Q000276:immunology / Q000378:metabolism / Q000821:virology; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis* / Q000378:metabolism
chemical_list: D000941:Antigens; D018984:Epitopes, T-Lymphocyte; D009698:Nucleoproteins; D010446:Peptide Fragments; D011948:Receptors, Antigen, T-Cell; D014409:Tumor Necrosis Factor-alpha; C094246:nucleoprotein peptide 118-126, lymphocytic choriomeningitis virus; D007371:Interferon-gamma; D010047:Ovalbumin