title: Antigen dose-dependent suppression of murine IgE responses is mediated by CD4(-)CD8(-) double-negative T cells.
abstract: BACKGROUND
  The IgE response against protein antigens is profoundly influenced by the dose used for sensitization.
  
  
  OBJECTIVE
  The aim of the study was to identify immune cells that are involved in antigen dose-dependent regulation of IgE formation.
  
  
  METHODS
  Wild-type mice as well as T helper (Th)1-deficient IL-12p40(-/-) and IFN-gamma(-/-) mice were immunized by repeated intraperitoneal injection of either low doses (K01 mice) or high doses (K100 mice) of keyhole limpet haemocyanin adsorbed to aluminium hydroxide. Splenocytes of immunized mice were restimulated in vitro and antigen-dependent T cell proliferation and cytokine production were measured. The frequency of regulatory T cell subsets among splenocytes from K01 and K100 mice was compared using fluorocytometry and RT-PCR analysis. Splenocytes or T cell subpopulations were transferred into naïve mice and the effect of lymphocyte transfer on IgE production after priming of recipients with low antigen doses was determined.
  
  
  RESULTS
  Specific IgE production was considerably impaired in K100 mice. Antigenic restimulation revealed hypoproliferation of K100 splenocytes and reduced production of Th2 cytokines IL-4, IL-5 and IL-13, but no induction of IFN-gamma production. Moreover, lymphocytes from K01 and K100 mice did not show significant differences in the expression of molecules associated with the phenotype or activity of conventional regulatory T cells. Transfer of splenocytes or purified T cells from K100 mice substantially suppressed the induction of IgE production in the recipients in an antigen- and isotype-specific manner. Neither CD4(+) nor CD8(+) T cells from K100 mice were able to inhibit IgE formation; instead, we identified CD4(-)CD8(-) double-negative T cells (dnT cells) as the principal T cell population, which potently suppressed IgE production.
  
  
  CONCLUSIONS
  Our data demonstrate that CD4(-)CD8(-) dnT cells play a major role in the regulation of IgE responses induced by high antigen doses.
authors.affiliation: The Clinical Research Unit Allergology, Department of Dermatology, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Barwig
authors.forename: V
authors.initials: V
authors.lastname: Raker
authors.forename: E
authors.initials: E
authors.lastname: Montermann
authors.forename: S
authors.initials: S
authors.lastname: Grabbe
authors.forename: A B
authors.initials: AB
authors.lastname: Reske-Kunz
authors.forename: S
authors.initials: S
authors.lastname: Sudowe
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000166:cytology / Q000276:immunology; D015704:CD4 Antigens / Q000378:metabolism*; D016827:CD8 Antigens / Q000378:metabolism*; D002454:Cell Differentiation; D004306:Dose-Response Relationship, Immunologic; D006433:Hemocyanins / Q000008:administration & dosage* / Q000276:immunology; D006969:Hypersensitivity, Immediate / Q000276:immunology; D007114:Immunization; D007073:Immunoglobulin E / Q000097:blood*; D007165:Immunosuppression Therapy; D008213:Lymphocyte Activation; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D050378:T-Lymphocytes, Regulatory / Q000276:immunology*
chemical_list: D015704:CD4 Antigens; D016827:CD8 Antigens; D007073:Immunoglobulin E; D006433:Hemocyanins; C032808:keyhole-limpet hemocyanin