CD4 and infection: At various time points after infection, higher number of CD4+ and CD8+ T cells were recruited to the lungs and MLN of WT mice compared to TLR4−/− mice, with significant differences observed from days 3 to 8 p.i. in the lungs and days 5 to 8 p.i. in the MLN compartment (Fig. 3B and 3C).