Figure 4. γδ T cells inhibit Treg cell responses in vivo.

(A, B) CD3⁺ T cells derived from congenic wild type mice (CD90.1) were left untreated or depleted of γδ T cells followed by intravenous transfer (5×10⁶) into Il23r^−/− hosts and immunization with MOG_35–55 plus CFA one day later. (A) After in vivo sensitization, donor cells were re-isolated from draining lymph nodes and analyzed for expression of γδ-TCR and Foxp3 by flow cytometry. (B) Fraction of Foxp3⁺ Treg cells within the CD4⁺ T cell compartment of substituted cells (CD90.1). (C, D) γδ T cells inhibit the conversion of conventional T cells into Foxp3⁺ Treg cells in vivo: Foxp3⁻ 2D2 responder T cells were sorted by flow cytometry from 2D2 × Foxp3gfp.KI mice and transferred iv into Rag1^−/− recipients without or with co-transfer of γδ T cells from wild type donors. Host mice were immunized with MOG_35–55 plus CFA and treated with a monoclonal antibody to IL-6R ip to prevent CFA-induced IL-6 from overriding γδ T cell effects on the conversion of conventional T cells into Foxp3⁺ Treg cells. On day 15 after immunization, 2D2 cells were re-isolated from lymph nodes, spleen, and CNS, and the frequency of MOG_35–55 specific Foxp3 (GFP)⁺ Treg cells was measured by flow cytometry (C). The rate of 2D2 T cells converted into antigen specific Foxp3⁺ Treg cells is depicted for the various lymphoid compartments and the CNS. Mean + SD, n=3 to 4 (D).