title: TNF-alpha antagonism generates a population of antigen-specific CD4+CD25+ T cells that inhibit protective immunity in murine histoplasmosis.
abstract: In both humans and mice, treatment with TNF-alpha antagonists is associated with serious infectious complications including disseminated histoplasmosis. The mechanisms by which inhibition of endogenous TNF-alpha alter protective immunity remain obscure. Herein, we tested the possibility that neutralization of this cytokine triggered the emergence of T cells that dampen immunity. The lungs of mice given mAb to TNF-alpha contained a higher proportion and number of CD4+CD25+ cells than controls. This elevation was not observed in IFN-gamma- or GM-CSF-deficient mice or in those given a high inoculum. Phenotypic analysis revealed that these cells lacked many of the characteristics of natural regulatory T cells, including Foxp3. CD4+CD25+ cells from TNF-alpha-neutralized mice suppressed Ag-specific, but not nonspecific, responses in vitro. Elimination of CD25+ cells in vivo restored protective immunity in mice given mAb to TNF-alpha and adoptive transfer of CD4+CD25+ cells inhibited immunity. In vitro and in vivo, the suppressive effect was reversed by mAb to IL-10. Thus, neutralization of TNF-alpha is associated with the induction of a population of regulatory T cells that alter protective immunity in an Ag-specific manner to Histoplasma capsulatum.
authors.affiliation: Division of Infectious Diseases, Veterans Affairs Hospital, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA. george.deepe@uc.edu
authors.forename: George S
authors.initials: GS
authors.lastname: Deepe
authors.forename: Reta S
authors.initials: RS
authors.lastname: Gibbons
mesh_terms: D019264:Adoptive Transfer; D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D015704:CD4 Antigens / Q000032:analysis; D006660:Histoplasmosis / Q000276:immunology*; D007109:Immunity / Q000187:drug effects; D016753:Interleukin-10 / Q000378:metabolism; D053645:Interleukin-2 Receptor alpha Subunit / Q000032:analysis; D051379:Mice; D008815:Mice, Inbred Strains; D050378:T-Lymphocytes, Regulatory / Q000276:immunology* / Q000637:transplantation; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors*
chemical_list: D000911:Antibodies, Monoclonal; D015704:CD4 Antigens; D053645:Interleukin-2 Receptor alpha Subunit; D014409:Tumor Necrosis Factor-alpha; D016753:Interleukin-10