ABSTRACT
In response to infection, naïve CD4+ T cells differentiate into two subpopulations: T follicular helper (TFH) cells, which support B cell antibody production, and non-TFH cells, which enhance innate immune cell functions. Interleukin-2 (IL-2), the major cytokine produced by naïve T cells, plays an important role in the developmental divergence of these populations. However, the relationship between IL-2 production and fate determination remains unclear. Using reporter mice, we found that differential production of IL-2 by naïve CD4+ T cells defined precursors fated for different immune functions. IL-2 producers, which were fated to become TFH cells, delivered IL-2 to nonproducers destined to become non-TFH cells. Because IL-2 production was limited to cells receiving the strongest T cell receptor (TCR) signals, a direct link between TCR-signal strength, IL-2 production, and T cell fate determination has been established.
Subject(s)
CD4-Positive T-Lymphocytes/immunology , Gene Expression , Interleukin-2/genetics , Receptors, Antigen, T-Cell/metabolism , T-Lymphocytes, Helper-Inducer/immunology , Animals , Chromatin/metabolism , Genes, Reporter , Lymphocyte Activation/genetics , Mice , Mice, Transgenic , Proto-Oncogene Proteins c-bcl-2/genetics , Receptors, Antigen, T-Cell/genetics , Transcription Factors/metabolismABSTRACT
TGF-ß1 is involved in many pathological conditions, including autoimmune disorders, cancer, and cardiovascular and allergic diseases. We have previously found that TGF-ß1 can suppress IgE-mediated mast cell activation of human and mouse mast cells. IL-33 is a member of the IL-1 family capable of inducing mast cell responses and enhancing IgE-mediated activation. In this study, we investigated the effects of TGF-ß on IL-33-mediated mast cell activation. Bone marrow-derived mast cells cultured in TGF-ß1, ß2, or ß3 showed reduced IL-33-mediated production of TNF, IL-6, IL-13, and MCP-1 in a concentration-dependent manner. TGF-ß1 inhibited IL-33-mediated Akt and ERK phosphorylation as well as NF-κB- and AP-1-mediated transcription. These effects were functionally important, as TGF-ß1 injection suppressed IL-33-induced systemic cytokines in vivo and inhibited IL-33-mediated cytokine release from human mast cells. TGF-ß1 also suppressed the combined effects of IL-33 and IgE-mediated activation on mouse and human mast cells. The role of IL-33 in the pathogenesis of allergic diseases is incompletely understood. These findings, consistent with our previously reported effects of TGF-ß1 on IgE-mediated activation, demonstrate that TGF-ß1 can provide broad inhibitory signals to activated mast cells.
