CD4 and susceptibility to pneumonia measurement: Consistent with our hypothesis, there were more RORγt+ and T-bet+ CD4+ T cells in the mediastinal LNs of the SSTI→Pna group, compared with the Pna or Pna→Pna groups, suggesting that SSTI primed greater expansion of Th17 and Th1 cells in the dLNs following secondary pneumonia than did primary pneumonia (Figures 3B, C 2°).