title: Human CD4+ T lymphocytes with remarkable regulatory functions on dendritic cells and nickel-specific Th1 immune responses.
abstract: The contribution of T helper (Th) and T cytotoxic (Tc) type 1 lymphocytes in the expression of allergic contact dermatitis to haptens has been amply documented. Conversely, the existence of T cell-based regulatory mechanisms has been poorly investigated. Here, we examined the properties of a subset of nickel-specific CD4+ T cells displaying the cytokine profile (IL-10 , IL-5 , IFN-gamma+/-, IL-4+/-) of T regulatory cells 1 (Tr1) and with the potential to down-modulate immune responses to nickel. Tr1 clones were isolated from skin challenged with NiSO4 and peripheral blood of nickel-allergic patients, and from the blood of healthy individuals. Tr1 clones expressed CD25, CD28, CD30, CD26, and the IL-12 receptor beta2 chain upon activation, whereas the lymphocyte activation antigen-3 was present on 50% of the clones. Monocytes precultured with Tr1 cells in the presence of nickel, or treated with Tr1-derived supernatant, exhibited a markedly diminished capacity to stimulate nickel-specific Th1 responses. Tr1 supernatants also blocked the differentiation of dendritic cells (DC) from monocytes, as well as DC maturation and IL-12 production induced by lipopolysaccharide. As a consequence, the ability of DC to stimulate nickel-specific Th1 and Tc1 responses was greatly impaired. These inhibitory effects were completely prevented by IL-10, but not IL-5, neutralization. In aggregate, the results indicate that Tr1 cells can potently regulate the expression of Th1-mediated allergic diseases via release of IL-10.
authors.affiliation: Laboratory of Immunology, Istituto Dermopatico dell'Immacolata, IRCCS, Rome, Italy. cavani@idi.it
authors.forename: A
authors.initials: A
authors.lastname: Cavani
authors.forename: F
authors.initials: F
authors.lastname: Nasorri
authors.forename: C
authors.initials: C
authors.lastname: Prezzi
authors.forename: S
authors.initials: S
authors.lastname: Sebastiani
authors.forename: C
authors.initials: C
authors.lastname: Albanesi
authors.forename: G
authors.initials: G
authors.lastname: Girolomoni
mesh_terms: D000328:Adult; D017951:Antigen Presentation / Q000502:physiology; D000938:Antigen-Presenting Cells / Q000276:immunology; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D002454:Cell Differentiation; D016207:Cytokines / Q000378:metabolism; D003713:Dendritic Cells / Q000276:immunology*; D017449:Dermatitis, Allergic Contact / Q000276:immunology; D005434:Flow Cytometry; D006801:Humans; D008875:Middle Aged; D009532:Nickel / Q000276:immunology*; D018417:Th1 Cells / Q000187:drug effects / Q000276:immunology*
chemical_list: D016207:Cytokines; D009532:Nickel