Toll-like receptors: balancing host resistance with immune tolerance.

Recent advances in the field of Toll-like receptors (TLRs) have established their importance for acute innate immune responses and their fundamental requirement for initiation of CD4(+) T-cell responses. Current directions in the field have been towards understanding the role of cytokines secreted by professional antigen-presenting cells in response to TLR ligands and also pathological manifestations in terms of increased production of rheumatoid factors due to TLR ligation on B cells. Thus, it is becoming clear that TLRs are important for induction of adaptive immune responses, but misguided responses can lead to autoimmune pathology.