TLR2 and infection: Interestingly, pneumolysin induced proinflammatory responses in primary macrophages in synergy with TLR2 ligands derived from S. pneumoniae, in particular peptidoglycan and whole pneumococcal cell walls (Malley et al., 2003; Srivastava et al., 2005), suggesting that during infection with intact pneumococci, the combined action of TLR4 and TLR2 may facilitate an optimal innate immune response.