Regarding the importance of CD4+ T cells in formation of iBALT tertiary germinal center-like structures [121–126], and that we saw increases in lung-resident Th1 and Tfh-like cells in heterologously primed mice, the differences in cellular composition or iBALT formation kinetics with either LCMV infection or adjuvanted rGP immunization priming compared to primary influenza infection warrants further investigation. Here, CD4 is linked to influenza.