ABSTRACT
IL-4 was found to be the essential differentiation factor for Th2 cells and simultaneously to be a potent inhibitor of Th1 development that is induced by IFN-gamma and IL-12. Furthermore, it was demonstrated that TGF-beta can also inhibit Thl development. In this work, we demonstrate that polyclonal activation of Mel-14highCD4+ T cells by immobilized anti-alphabetaTCR mAb together with a mixture of IL-4 and TGF-beta can lead to the development of both Th1 and Th2 cells, depending on the concentration of these cytokines. Additional experiments revealed that Th1 induction by a combination of IL-4 and TGF-beta depends on the presence of endogenous IFN-gamma, and that this alternative Th1 development is further enhanced by IL-12, but is not dependent on this cytokine. Moreover, naive OVA323-339-specific Th cells that were stimulated by APCs and OVA323-339 peptide differentiated toward Th1 cells after priming in the presence of IL-4 in combination with TGF-beta. Hence, this finding confirmed the results obtained by polyclonal activation of naive CD4+ Th cells and implicates that this alternative Th1 development may also occur in vivo under the influence of TGF-beta and IL-4 independently of the Th1-promoting effect of IL-12.
Subject(s)
Interferon-gamma/physiology , Interleukin-12/physiology , Interleukin-4/pharmacology , Lymphocyte Activation/drug effects , Th1 Cells/drug effects , Transforming Growth Factor beta/pharmacology , Animals , Cell Differentiation/drug effects , Dose-Response Relationship, Immunologic , Drug Synergism , Female , Interferon-gamma/biosynthesis , Interleukin-12/pharmacology , Interleukin-4/biosynthesis , Male , Mice , Mice, Inbred BALB C , Mice, Inbred C3H , Mice, Inbred DBA , Mice, Transgenic , Osmolar Concentration , Receptors, Antigen, T-Cell, alpha-beta/genetics , Receptors, Antigen, T-Cell, alpha-beta/immunology , Th1 Cells/cytology , Th1 Cells/metabolism , Th2 Cells/cytology , Th2 Cells/drug effectsABSTRACT
The development of naive dense CD4+ T cells from different mouse strains toward Th1 cells, as monitored by measuring secondary IFN-gamma production, was affected by TGF-beta 2 in a differential way. Th1 cell development of naive CD4+ T cells from strains C57Bl/6, BALB/c, and NMRI primed by immobilized anti-CD3 mAb was strongly inhibited in the presence of TGF-beta 2. Even when the Th1 cell-inducer IL-12 was added, the same effect of TGF-beta 2 was observed. In contrast, Th1 development was substantially promoted by TGF-beta 2 with T cells from C3H/He and CBA/J mice. Further analyses using CD4+ T cells from (C57Bl/6xCBA/J)F1 hybrids or DBA/1 mice showed that Th1 development was inhibited by TGF-beta 2 if the T cells were activated by anti-CD3 mAb, but it was enhanced upon costimulation with anti-CD28 mAb. Determination of primary IL-2 production revealed that T cells from (C57Bl/6xCBA/J)F1 and DBA/1 mice produced low amounts of IL-2 following stimulation by anti-CD3 mAb alone and comparatively high amounts after coactivation by anti-CD28 mAb. In the presence of TGF-beta 2, the production of IL-2 was completely suppressed if such T cells were activated solely by anti-CD3 mAb, but it was only partially inhibited after costimulation by anti-CD28 mAb. Furthermore, TGF-beta 2-promoted Th1 development of such T cells was strongly inhibited after neutralization of endogenously produced IL-2 and completely restored by the addition of human IL-2. Thus, our results indicate that the TGF-beta 2-mediated stimulation of Th1 cell development requires the presence of relatively high concentrations of IL-2. Therefore, the opposing effect of TGF-beta 2 on the Th1 cell development of naive CD4+ T cells from different mouse strains appears to be the result of the variable potency of the respective CD4+ T cells to produce IL-2 in the presence of TGF-beta 2.
Subject(s)
CD4-Positive T-Lymphocytes/immunology , Th1 Cells/immunology , Transforming Growth Factor beta/physiology , Animals , Cell Differentiation/immunology , Cell Separation , Cells, Cultured , Female , Humans , Interleukin-2/biosynthesis , Interleukin-2/metabolism , Interleukin-2/physiology , Lymphocyte Activation , Male , Mice , Mice, Inbred BALB C , Mice, Inbred C3H , Mice, Inbred C57BL , Mice, Inbred CBA , Mice, Inbred DBAABSTRACT
IL-9 is produced in vitro by activated CD4+ T cell lines of the Th2 subtype and by naive CD4+ T cells. Here we show that T cell lines stimulated with Con A in the presence of accessory cells (AC) such as irradiated spleen cells or bone marrow-derived macrophages produced substantially more IL-9 than T cells stimulated with Con A alone. These data suggest that AC influence the production of IL-9 through accessory signals that result in an at least 10-fold increase of IL-9 secretion by the respective T cells. Addition of IL-1 to T cells activated by Con A, PHA, or anti-CD3 antibodies revealed that this monokine was responsible for the potentiation of IL-9 production. This finding was confirmed by applying anti-IL-1 antibodies. The production of other lymphokines, namely, IL-3, IL-4, and IL-6, by activated T cells was not or only marginally enhanced in the presence of AC or IL-1, thus indicating that the synthesis of IL-9 is regulated differently from that of other Th2-derived lymphokines. Furthermore, it was demonstrated by Northern blot analysis that IL-1 increases IL-9 expression at the pretranslational level. Because IL-1 alone failed to induce the production of IL-9 by T cells, this monokine acts as a costimulator in combination with a T cell receptor-mediated signal.
Subject(s)
Interleukin-1/physiology , Interleukin-9/metabolism , Lymphocyte Activation , T-Lymphocyte Subsets/metabolism , T-Lymphocytes, Helper-Inducer/metabolism , Animals , Antigen-Presenting Cells/physiology , CD4-Positive T-Lymphocytes/metabolism , Gene Expression , Interleukin-2/genetics , Interleukin-3/biosynthesis , Interleukin-4/biosynthesis , Interleukin-4/genetics , Interleukin-6/biosynthesis , Interleukin-9/genetics , Membrane Proteins/physiology , Mice , Mice, Inbred Strains , RNA, Messenger/genetics , Recombinant ProteinsABSTRACT
The protein antigens conalbumin (CA) and ovalbumin (OVA) are known to require uptake into antigen-presenting cells (APC) for their presentation to major histocompatibility complex (MHC) class II-restricted T cells. In both cases proteolytic cleavage is thought to be a necessary step for the generation of the respective antigenic peptides. A specific inhibitor of the endosomal protease cathepsin B, Cbz-Phe-Ala-CHN2, blocks the presentation of both CA and OVA, whereas this inhibitor has no effect on the presentation of a processing-independent OVA peptide. Furthermore, the presentation of insulin, an antigen that needs processing but no proteolytic cleavage, is enhanced when cathepsin B is inhibited during antigen pulsing. When the APC were treated with an inhibitor of acid proteases, the CA response was not affected, while the presentation of OVA was diminished under these conditions. To estimate the relevance of these findings for the generation of the antigenic CA peptide, extracellular digestions of CA by cathepsin B were carried out. The fragment(s) present in these digests was recognized by T cells without further processing. Furthermore, the time-course of intra- and extracellular CA processing with respect to the capacity to stimulate T cells was similar. Taken together these data suggest that degradation by cathepsin B may be sufficient in vivo to generate the antigenic CA fragment. On the other hand, the blocking of cathepsin B does not appear to have an adverse effect on the general mechanisms of antigen presentation.
