Inhibition of Initial T cell priming by Lymph node Stromal Populations.

<p>(<b>a</b>) Three cell lines were isolated representing FRC (FRC.5: CD31−/gp38+)), LEC (LEC.6: CD31+gp38+), and BEC (BEC.7: CD31+gp38−). (<b>b</b>) Contrast images of each line showing differences in morphology consistent with their in vivo function. (<b>c</b>) 10⁵ CFSE-labeled OTI T cells were incubated in 96-well round-bottom wells in the presence of 10⁴ BMDCs either unpulsed (NS) or pulsed (+SL8) with the indicated concentrations of SL8 peptides. 5×10³ stromal cells were added where indicated. Cells were analyzed by FACS after 48 hours. (<b>d</b>) CFSE proliferation assays were performed identically to (<b>a</b>) but included freshly purified gp38+CD31− FRC or an equal number of unfractionated total (including T cells, B cells, etc.) from collagenase digestion of lymph nodes. (<b>e</b>) Proliferation assays were performed identically to those in (<b>c,d</b>) but included mouse embryonic fibroblasts (MEF) or NIH-3T3 cells as 3^rd party cell types. All experiments are representative of at least 3 similar trials.