Human retinal pigment epithelium-induced CD4+CD25+ regulatory T cells suppress activation of intraocular effector T cells

Murine retinal pigment epithelial (RPE) cells suppress T-cell activation by releasing soluble inhibitory factors and promote the generation of regulatory T cells in vitro. These T cells exposed to RPE supernatants (RPE-induced Treg cells) can suppress the activation of bystander effector T cells via the production of transforming growth factor-beta (TGF beta). In the present study, we showed that human RPE-induced Treg cells are also able to acquire regulatory function when human RPE cell lines were pretreated with recombinant TGF beta 2. These RPE-induced Treg cells produced TGF beta 1 and IL-10 but not IFN gamma, and they significantly suppressed the activation of target cell lines and intraocular T-cell clones established from patients with active uveitis. Moreover, CD4(+)CD25(+) RPE-induced Treg cells expressed CTLA-4 and Foxp3 molecules, and the CD25(+) Treg cells profoundly suppressed the T-cell activation. Thus, in vitro manipulated Treg cells acquire functions that participate in the establishment of immune tolerance in the eye. (C) 2010 Elsevier Inc. All rights reserved.