IL7R and viral infectious disease: To discern if GVHD-induced FRC injury provoked a similar influx of LTi cells as observed in viral infection, we next tracked numbers of LTi cells (defined as lineage–CD117+IL-7Rα+RORγt+) in both the F→M model and B6→129 model (see Supplemental Figure 4A for gating strategy), using congenic markers to identify their host/donor origin.