Toll-like receptors and control of mycobacterial infection in mice.

Microbial products including mycobacterial antigens are recognized by distinct Toll-like receptors (TLRs) resulting in activation of cells of the innate immune system. Ablation of most of the TLR signalling in mice deficient for the common adaptor protein MyD88 revealed that TLRs are crucial for the activation of an innate immune response as MyD88-deficient mice are highly sensitive to infection with Mycobacterium tuberculosis. Despite the profound defect of the innate immune response, MyD88 deficiency allows the emergence of an adaptive immunity. These data demonstrate that activation of multiple TLRs contributes to an efficient innate response to mycobacteria, while MyD88-dependent signalling is dispensable to generate adaptive immunity.