TMV-associated TGF-β1 and IL-10 promote Treg expansion.

<p>(<b><u>A</u></b>) Flow cytometry analysis of TGF-β1 and IL-10 expression on TMV purified from OVCAR-3 SN and coated onto latex beads. (<b><u>B</u></b>) CD4⁺CD25^highFOXP3⁺ T cells were cultured with OKT3, anti-CD28 and IL-2 (150 IU/mL) +/− TMV for 72 h at 37°C in the presence of Golgistop and then stained for CD4, CD3, CD25 and intracellular TGF-β1 and IL-10. Expression of both cytokines was up-regulated in the presence of TMV (p<0.05). (<b><u>C</u></b>) SMAD2/3 and STAT3 phosphorylation in Treg before and after exposure to TMV. Representative results are from one of three independent experiments for <b><u>A</u></b>, <b><u>B</u></b> and <b><u>C</u></b>. (<b><u>D</u></b>) The percentage of CD4⁺CD25^highFOXP3⁺ T cells increased among CD4⁺CD25⁺ T cells cultured in the presence of TMV but not DC-derived MV. Neutralizing anti-TGF-β1 and/or anti-IL-10 Abs inhibited the induction of Treg by TMV. Non-blocking IgG isotype control Abs were used as controls. Asterisks indicate decreases (p<0.05) in Treg percentages in the presence of neutralizing Abs. Results are means ± SD of three independent experiments.