Regulation of T Cell Priming by Lymphoid Stroma Figure 4. A proximal role for iNOS during T cell priming by Lymphoid Stroma. (a) Proliferation of OTI cells stimulated with peptide-loaded BMDCs in the presence or absence of FRC.5 cells and either a broad NOS inhibitor (L-NMMA) or the iNOS inhibitor,1400W. (b–c) Proliferation assays identical to that in (a) but measuring the effect of NOS inhibitors under various concentrations of FRC.5 cells. (b) % Blasts quantified, demonstrating FRC inhibition is reversible with iNOS blockade across a range of FRC concentration. (d) Proliferation of OTI cells stimulated with peptide-loaded iNOS-/- BMDCs with or without added FRC. All assays were repeated in a minimum of 2 trials, and typically 4–6 independent trials and all conditions PLoS ONE | www.plosone.org 6 November 2011 | Volume 6 | Issue 11 | e26138