sq-23377 and Schistosomiasis-mansoni

PMA and ionomycin cause T cell cytokine production. We report that ionomycin alone induces IL-4 and IFN-gamma, but not IL-2, from in vivo- and in vitro-generated murine Th2 and Th1 cells. Ionomycin-induced cytokine production requires NFAT, p38, and calmodulin-dependent kinase IV (CaMKIV). Ionomycin induces p38 phosphorylation through a calcium-dependent, cyclosporine A-inhibitable pathway. Knocking down ASK1 inhibits ionomycin-induced p38 phosphorylation and IL-4 production. Ionomycin also activates CaMKIV, which, together with p38, induces AP-1. Cooperation between AP-1 and NFAT leads to Il4 gene transcription. p38 also regulates IL-4 production by mRNA stabilization. TCR stimulation also phosphorylates p38, partially through the calcium-dependent pathway; activated p38 is required for optimal IL-4 and IFN-gamma.

Topics: Animals; Calcium Signaling; Cell Differentiation; Cells, Cultured; Interferon-gamma; Interleukin-4; Ionomycin; Lymphocyte Activation; MAP Kinase Signaling System; Mice; Mice, Inbred C57BL; Mice, Knockout; Mice, Transgenic; p38 Mitogen-Activated Protein Kinases; RNA Stability; RNA, Messenger; Schistosomiasis mansoni; Th2 Cells; Transcription, Genetic; Up-Regulation

Activated CD4(+) T helper cells (Th) comprise at least two functionally distinct subsets, Th1 and Th2, which mediate different immunological effector functions. Experimental leishmaniasis is widely used to study the effector function of Th cell subsets in vivo. Healing and nonhealing Leishmania major infections have been correlated with polarized Th1 and Th2 responses, respectively. In the study presented here, a stable cell surface marker expressed on Th2 cells, T1/ST2, has been used to assess the distribution of CD4(+) T1/ST2(+) T cells in different organs of healer and nonhealer strains of mice during the course of L. major infection. The frequency of CD4(+) T cells expressing the T1/ST2 cell surface marker and Th2 cytokines in the lymphoid organs was low in both strains of infected mice; however, CD4(+) T1/ST2(+) T cells could be enriched from the lymphoid organs of infected nonhealer but not from healer strains of mice. The highest frequency of CD4(+) T1/ST2(+) T cells was detected in the footpads of mice with nonhealing disease, showing that CD4(+) T1/ST2(+) T cells home to the footpads. Since the majority of parasites persist at the local site of infection in nonhealing BALB/c mice, these results show that CD4(+) T1/ST2(+) T cells are localized at the site of active infection and inflammation in this model.

Topics: Animals; CD5 Antigens; Cell Differentiation; Chronic Disease; Disease Susceptibility; Female; Interleukin-1 Receptor-Like 1 Protein; Ionomycin; Leishmania major; Leishmaniasis, Cutaneous; Lymph Nodes; Lymphocyte Activation; Lymphoid Tissue; Membrane Proteins; Mice; Mice, Inbred BALB C; Mice, Inbred C57BL; Mice, Inbred CBA; Organ Specificity; Phenotype; Receptors, Interleukin; Schistosomiasis mansoni; Specific Pathogen-Free Organisms; Spleen; T-Lymphocyte Subsets; Tetradecanoylphorbol Acetate; Th2 Cells

Previous work from this laboratory has indicated that murine memory T cells differ from virgin T cells in that the former are more resistant to agents that alter intracellular [Ca]i. We have used this difference to devise a method for separating virgin from memory T cells by centrifugation over an ionomycin-containing Percoll step gradient after brief exposure to 2 microM ionomycin. Under these conditions, those T cells that are most sensitive to ionomycin-induced changes in [Ca]i become more dense and therefore travel further into the Percoll/ionomycin gradient than cells that are more resistant to ionomycin. We show that the ionomycin-resistant cell population is enriched for cells that express high levels of Pgp-1 (CD44), and low levels of CD45RB, and thus appears to consist largely of memory T cells. Both CD4 and CD8 cells can be divided into Pgp-1hi and Pgp-1lo subsets in this way. Cells recovered from such a gradient and washed to remove the ionomycin appear normally functional, i.e., neither more nor less responsive to mitogens and costimuli than untreated cells. Limiting dilution methods show that the ionomycin-sensitive (virgin) subset contains most of the Con A-responsive precursors for cytotoxicity, and most of the cells able to produce IL-2 in responses to Con A or staphylococcal enterotoxin B. Ag-specific helper memory cells are, however, found predominantly in the ionomycin-resistant fraction of the spleen and draining lymph nodes of mice infected with Schistosoma mansoni. Changes in resistance to calcium signal development may represent a fundamental distinction between virgin and memory T cells, and could contribute to differences in activation requirements between these two cell subsets.

Topics: Animals; Antigens, CD; Calcium; CD4 Antigens; CD8 Antigens; Cell Separation; Centrifugation, Density Gradient; Concanavalin A; Cytotoxicity, Immunologic; Histocompatibility Antigens; Immunity, Cellular; Immunologic Memory; Ionomycin; Leukocyte Common Antigens; Lymphocyte Activation; Mice; Receptors, Lymphocyte Homing; Schistosomiasis mansoni; T-Lymphocyte Subsets; T-Lymphocytes, Cytotoxic