TLR2 and infection: TLRs modulate the induction of hundreds of host genes through a complex network of signalling that allows for the appropriate response to a microbial pathogen.35 In order to investigate how TLR2 and TLR4 influence mycobacteria induced cytokine secretion from neutrophils, monocytes, alveolar A549 and PBE epithelial cells, the cells were treated with Abs against TLR2 and/or TLR4 before infection with live BCG (Figure 5).