In vitro human TGF-β treatment converts CD4+CD25− T cells into induced T regulatory like cells

In mammals, induced T regulatory cells (iTregs) are produced by treating CD4+CD25− cells in vitro with TGF-β in the presence of anti-CD3 and IL-2. Chicken CD4+CD25− cells were treated in vitro with TGF-β, anti-CD3, anti-CD28 and IL-2 and analyzed for suppressive properties, IL-10 and IL-2 mRNA amounts. TGF-β treatment decreased (P < 0.01) CD4+CD25− cell proliferation by 45% at 5 d of cell culture with no increase in dead cell population. CD4+CD25− cells treated with 5 ng TGF-β for 5 d had 130-fold (P < 0.01) more IL-10 and 104-fold (P < 0.01) less IL-2 mRNA content than the 0 ng TGF-β treated groups. CD4+CD25− cells treated with 5 ng TGF-β for 5 d suppressed (P < 0.01) naïve cell proliferation compared to the 0 ng TGF-β treated groups. The results suggest the presence of iTreg-like cells in avian species.