Control of adaptive immune responses by Toll-like receptors.

Recently, there has been considerable interest in how adaptive immune responses are controlled by the innate immune system. In particular, researchers have focused on how the differentiation of CD4 T cells is directed upon priming by dendritic cells. The identification of the Toll-like receptors as a family of pattern-recognition receptors involved in controlling dendritic cell activation has focused attention on these receptors as possible regulators of adaptive immune responses. However, recent studies have suggested that Toll-like receptors may only control the induction of Th1 responses and that a separate system of recognition regulates Th2 responses.