TLR4 and pneumococcal infection: To determine the effect of TLR4 on the host resistance against pneumococcal infection, wild-type and TLR4-deficient mice were infected intra-nasally with S. pneumoniae. The survival (Fig 3A: P < 0.001), pulmonary bacterial clearance (Fig 3B: P = 0.004, 6 hours; P = 0.011, 12 hours) and pulmonary cytokine levels (Fig 3C: P = 0.009, 6 hours.