TLR2 and pneumococcal pneumonia: Considering that especially low TNF-α concentrations in the lungs early after induction of pneumococcal pneumonia are important for limiting the growth of S. pneumoniae (van der Poll et al., 1997; Rijneveld et al., 2001), this differential response may have contributed to the enhanced growth of S. pneumoniae PLN in TLR2 KO mice.