PD-1 expression profile on T cells undergoing Th1 or Th17 differentiation is not modified by the co-culture with MSC.

<p>Percentage of PD-1 expressing T cells during their differentiation toward (A) Th1 or (B) Th17 lineages (day 0, 1, 4 and 6 of the differentiation process) was detected by flow cytometry. Percentage of PD-1 expressing T cells in the presence or absence of MSC added either (C) at day 0 of the differentiation process or (D) on mature Th1 and Th17 cells. <i>P</i> values referred to PD-1 expression level on purified CD4⁺ T cells at day 0 of differentiation processes.