title: B7 and interleukin 12 cooperate for proliferation and interferon gamma production by mouse T helper clones that are unresponsive to B7 costimulation.
abstract: We have previously shown that dendritic cells isolated after overnight culture, which can express B7 and are potent stimulators of naive T cell proliferation, are relatively poor at inducing the proliferation of a panel of murine T helper 1 (Th1) clones. Maximal stimulation of Th1 clones was achieved using unseparated splenic antigen presenting cells (APC). An explanation for these findings is provided in the present study where we show that FcR+ L cells transfected with B7 stimulate minimal proliferation of Th1 clones in response to anti-CD3 antibodies, in contrast to induction of significant proliferation of naive T cells. However, addition of interleukin 12 (IL-12) to cultures of Th1 cells stimulated with anti-CD3 and FcR+ B7 transfectants resulted in a very pronounced increase in proliferation and interferon gamma (IFN-gamma) production. Exogenous IL-12 did not affect the B7-induced proliferation of naive T cells. This showed that whereas costimulatory signals delivered via B7-CD28 interaction are sufficient to induce significant proliferation of naive T cells activated through occupancy of the T cell receptor, Th1 T cell clones require cooperative costimulation by B7 and IL-12. This costimulation was shown to be specific by inhibition of proliferation and IFN-gamma production using chimeric soluble cytolytic T lymphocyte-associated antigen 4-human IgG1Fc (CTLA4-Ig) and anti-IL-12 antibodies. Furthermore, the significant antigen specific proliferation and IFN-gamma production by Th1 clones observed when splenocytes were used as APC was almost completely abrogated using CTLA4-Ig and anti-IL-12 antibodies. Thus two costimulatory signals, B7 and IL-12, account for the ability of splenic APC to induce maximal stimulation of Th1 clones. IL-10 downregulates the expression of IL-12 by IFN-gamma-stimulated macrophages and this may account largely for t the ability of IL-10 to inhibit APC function of splenic and macrophage APC for the induction of Th1 cell proliferation and IFN-gamma production. Indeed we show that IL-12 can overcome the inhibitory effect of IL-10 for the APC-dependent induction of proliferation and IFN-gamma production by Th1 clones. These results suggest that proliferation by terminally differentiated Th1 clones, in contrast to naive T cells, requires stimulation via membrane-bound B7 and a cytokine, IL-12. It is possible that these signals may result in the activation of unresponsive T cells during an inflammatory response. IL-10, by its role in regulating such innate inflammatory responses, may thus help to maintain these T cells in an unresponsive state.
authors.affiliation: DNAX Research Institute, Palo Alto, California 94304-1104.
authors.forename: E E
authors.initials: EE
authors.lastname: Murphy
authors.forename: G
authors.initials: G
authors.lastname: Terres
authors.forename: S E
authors.initials: SE
authors.lastname: Macatonia
authors.forename: C S
authors.initials: CS
authors.lastname: Hsieh
authors.forename: J
authors.initials: J
authors.lastname: Mattson
authors.forename: L
authors.initials: L
authors.lastname: Lanier
authors.forename: M
authors.initials: M
authors.lastname: Wysocka
authors.forename: G
authors.initials: G
authors.lastname: Trinchieri
authors.forename: K
authors.initials: K
authors.lastname: Murphy
authors.forename: A
authors.initials: A
authors.lastname: O'Garra
mesh_terms: D000069594:Abatacept; D000818:Animals; D000938:Antigen-Presenting Cells / Q000502:physiology; D015703:Antigens, CD; D000943:Antigens, Differentiation / Q000502:physiology; D018122:B7-1 Antigen / Q000502:physiology*; D001483:Base Sequence; D060908:CTLA-4 Antigen; D002460:Cell Line; D002999:Clone Cells; D005260:Female; D018796:Immunoconjugates; D007371:Interferon-gamma / Q000096:biosynthesis*; D016753:Interleukin-10 / Q000494:pharmacology; D018664:Interleukin-12; D007378:Interleukins / Q000502:physiology*; D008213:Lymphocyte Activation; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D006377:T-Lymphocytes, Helper-Inducer / Q000502:physiology*
chemical_list: D015703:Antigens, CD; D000943:Antigens, Differentiation; D018122:B7-1 Antigen; D060908:CTLA-4 Antigen; C556706:CTLA4 protein, human; C556707:Ctla4 protein, mouse; D018796:Immunoconjugates; D007378:Interleukins; D016753:Interleukin-10; D018664:Interleukin-12; D000069594:Abatacept; D007371:Interferon-gamma