title: Anti-leishmania effector functions of CD4+ Th1 cells and early events instructing Th2 cell development and susceptibility to Leishmania major in BALB/c mice.
abstract: Resistance and susceptibility to infection with the intracellular parasite, Leishmania major, are mediated by parasite-specific CD4+ Th1 and Th2 cells, respectively. It is well established that the protective effect of parasite-specific CD4+ Th1 cells is largely dependent upon the IFN-gamma produced. However, recent results indicate that the effect of Th1 cells on resolution of lesions induced by L. major in genetically resistant mice also requires a functional Fas-FasL pathway of cytotoxicity. In contrast to resistant mice, susceptible BALB/c mice develop aberrant Th2 responses following infection with L. major and consequently suffer progressive disease. These outcomes clearly depends upon the production of interleukin 4 (IL-4) early after infection. We have shown that a burst of IL-4 mRNA, peaking in draining lymph nodes of BALB/c mice 16 hrs after infection, occurs within CD4+ T cells that express V beta 4-V alpha 8 T cell receptors. In contrast to control and V beta 6-deficient mice, V beta 4-deficient BALB/c mice were resistant to infection, demonstrating the role of these cells in Th2 development. The early IL-4 response was absent in these mice, and Th1 responses occurred following infection. The LACK antigen of L. major induced comparable IL-4 production in V beta 4-V alpha 8 CD4+ T cells. Thus, the IL-4 required for Th2 development and susceptibility to L. major is produced by a restricted population of V beta 4-V alpha 8 CD4+ T cells after cognate interaction with a single antigen from this complex parasite. The IL-4 produced rapidly by these CD4+ T cells induces within 48 hours a state of unresponsiveness to IL-12 among parasite-specific CD4+ T cell precursors by downregulating the IL-12 receptor beta 2 chain expression.
authors.affiliation: WHO Immunology Research and Training Center, Institute of Biochemistry, University of Lausanne, Epalinges, Switzerland.
authors.forename: J A
authors.initials: JA
authors.lastname: Louis
authors.forename: F
authors.initials: F
authors.lastname: Conceiçao-Silva
authors.forename: H
authors.initials: H
authors.lastname: Himmelrich
authors.forename: F
authors.initials: F
authors.lastname: Tacchini-Cottier
authors.forename: P
authors.initials: P
authors.lastname: Launois
mesh_terms: D000818:Animals; D015704:CD4 Antigens / Q000276:immunology; D003602:Cytotoxicity, Immunologic; D004198:Disease Susceptibility / Q000276:immunology; D018320:Leishmania major / Q000276:immunology*; D016773:Leishmaniasis, Cutaneous / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D018417:Th1 Cells / Q000276:immunology*; D018418:Th2 Cells / Q000276:immunology*
chemical_list: D015704:CD4 Antigens