TLR4 and pneumonia: Indeed, whereas the patients studied by Kumpf et al. developed pneumonia predominantly caused by Gram-negative bacteria, known to be specifically recognized by TLR4, the children in our study were supposedly infected by Gram-positive Spn recognized by both TLR2 (and TLR1 and TLR6 as co-receptors) and TLR4. The fact that Pam3CSK4, a specific TLR2 ligand, was unable to induce potent IL-6 production in double-mutated LRTI children (TIRAP 180Leu/TLR1 248S or TIRAP 180Leu/TLR1 602S or TIRAP 180Leu/TLR6 249P) might reflect a defect within the TLR2 or TLR1 and TLR6 co-receptors.