Antigen-presenting cells are targets of regulatory T cells similar to those that mediate anterior chamber-associated immune deviation

Purpose: To identify the means by which in-vitro-generated regulatory T cells, similar to those in anterior chamber-associated immune deviation (ACAID), suppress antigen-specific T-cell responses. Methods: T regulators (T regs), generated by stimulating ovalbumin (OVA)-specific Tcr transgenic DOII.I0 T cells with OVA-pulsed, TGF-beta2-treated peritoneal exudates cells (PEC), or their supernatants were added to OVA-pulsed PEC that were used to activate DOII.I0 T cells in vitro or to suppress OVA-specific delayed hypersensitivity (DH) induction in vivo. Results: OVA-pulsed PECs exposed in vitro to TGF-beta-producing T regs or their supernatants failed to activate DOII.I0 T cells in vitro, and suppressed DH in mice immunized with OVA plus adjuvant. Conclusion: T cells exposed to TGF-beta(2)-pretreated, antigen-pulsed PECs secrete soluble factors, including active TGF-beta that regulate OVA-specific responses by forcing antigen-presenting cells to promote deviant T-cell activation in vitro and in vivo.