title: Gamma delta T cell-deficient mice have a down-regulated CD8+ T cell immune response against Encephalitozoon cuniculi infection.
abstract: Gamma(delta) T cells have been reported to play an essential effector role during the early immune response against a wide variety of infectious agents. Recent studies have suggested that the gamma(delta) T cell subtype may also be important for the induction of adaptive immune response against certain microbial pathogens. In the present study, an early increase of gamma(delta) T cells during murine infection with Encephalitozoon cuniculi, an intracellular parasite, was observed. The role of gamma(delta) T cells against E. cuniculi infection was further evaluated by using gene-knockout mice. Mice lacking gamma(delta) T cells were susceptible to E. cuniculi infection at high challenge doses. The reduced resistance of delta(-/-) mice was attributed to a down-regulated CD8+ immune response. Compared with parental wild-type animals, suboptimal Ag-specific CD8+ T cell immunity against E. cuniculi infection was noted in delta(-/-) mice. The splenocytes from infected knockout mice exhibited a lower frequency of Ag-specific CD8+ T cells. Moreover, adoptive transfer of immune TCR(alpha)beta+ CD8+ cells from the delta(-/-) mice failed to protect naive CD8(-/-) mice against a lethal E. cuniculi challenge. Our studies suggest that gamma(delta) T cells, due to their ability to produce cytokines, are important for the optimal priming of CD8+ T cell immunity against E. cuniculi infection. This is the first evidence of a parasitic infection in which down-regulation of CD8+ T cell immune response in the absence of gamma(delta) T cells has been demonstrated.
authors.affiliation: Department of Medicine, Dartmouth Medical School, Lebanon, NH 03756, USA.
authors.forename: M
authors.initials: M
authors.lastname: Moretto
authors.forename: B
authors.initials: B
authors.lastname: Durell
authors.forename: J D
authors.initials: JD
authors.lastname: Schwartzman
authors.forename: I A
authors.initials: IA
authors.lastname: Khan
mesh_terms: D019264:Adoptive Transfer; D000818:Animals; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology* / Q000469:parasitology* / Q000637:transplantation; D016207:Cytokines / Q000096:biosynthesis; D003602:Cytotoxicity, Immunologic / Q000235:genetics; D004306:Dose-Response Relationship, Immunologic; D015536:Down-Regulation / Q000235:genetics* / Q000276:immunology*; D009670:Encephalitozoon cuniculi / Q000235:genetics / Q000276:immunology*; D016890:Encephalitozoonosis / Q000235:genetics / Q000276:immunology* / Q000473:pathology / Q000517:prevention & control; D005260:Female; D020022:Genetic Predisposition to Disease; D007274:Injections, Intraperitoneal; D007275:Injections, Intravenous; D007371:Interferon-gamma / Q000008:administration & dosage; D018655:Lymphocyte Count; D008218:Lymphocytosis / Q000235:genetics / Q000276:immunology; D008231:Lymphopenia / Q000235:genetics / Q000276:immunology / Q000469:parasitology; D008264:Macrophages / Q000276:immunology / Q000469:parasitology; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000276:immunology; D016692:Receptors, Antigen, T-Cell, gamma-delta / Q000172:deficiency* / Q000235:genetics*; D013154:Spleen / Q000166:cytology / Q000276:immunology; D016176:T-Lymphocyte Subsets / Q000276:immunology / Q000469:parasitology / Q000473:pathology / Q000637:transplantation
chemical_list: D016207:Cytokines; D016693:Receptors, Antigen, T-Cell, alpha-beta; D016692:Receptors, Antigen, T-Cell, gamma-delta; D007371:Interferon-gamma