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Updated: Jun 8, 2026

In Vitro Differentiation of Human CD4+FOXP3+ Induced Regulatory T Cells (iTregs) from Naïve CD4+ T Cells Using a TGF-β-containing Protocol
Published on: December 30, 2016
Retinal pigment epithelial cells induce foxp3(+) regulatory T cells via membrane-bound TGF-β
Jose L Vega1, Daniel Saban, Yejun Carrier
1Center for Neurologic Diseases, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA.
Purpose:
It is speculated that retinal pigment epithelial (RPE) cells convert naïve T cells into regulatory T cells (Tregs) via soluble factors such as transforming growth factor beta (TGF-β). Yet presence or absence of similar membrane-bound mechanisms on RPE cells has yet to be addressed. Here the authors investigated the expression of surface TGF-β by RPE cells and its participation in the conversion of naive T cells into Tregs.
Methods:
They examined the phenotype of murine CD4(+) CD25(-) T cells activated in the presence of ethanol-fixed RPE cell layers as fixation preserves membrane structure while preventing the secretion of soluble factors.
Results:
Fixed RPE cells supported the development of a de novo foxp3(+) Th3-like suppressor phenotype in activated peripheral naïve T cells through an interaction that required both RPE-derived surface TGF-β, and T-cell derived TGF-β1.
Conclusions:
Aside from soluble factors, RPE-derived surface TGF-β can convert activated naïve T cells into Tregs.
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