Fig. 4.
GARP is required for the surface expression of latent TGF-β1. (A) FACS-sorted Tregs (CD25hi), naïve (CD45RA+), and memory (CD45RO+) T cells were activated for 5 days in the absence or presence of TGF-β1 then rested for 7 days and restimulated for 48 h without TGF-β1 before analysis of FOXP3 with surface GARP and LAP expressions. (B) Tregs were transfected with nonspecific (siNS) or FOXP3 (siFOXP3) siRNA and cultured for 5 days before activation for 48 h and analysis of FOXP3 with surface GARP and LAP expressions. (C) Naïve T cells were transduced with control (vector) or GARP encoded RFP-expressing lentiviral vectors and expanded for 7 days with anti-CD3/CD28 Dynabeads before restimulation for 48 h to evaluate for surface GARP and LAP (Left) and intracellular FOXP3 expressions among RFP+ and RFP− cells (Right). Data are representative of 3 independent experiments. Numbers indicate percentage in each quadrant.