Toll-like receptors control activation of adaptive immune responses


Mechanisms that control the activation of antigen-specific immune responses in vivo are poorly understood. It has been suggested that the initiation of adaptive immune responses is controlled by innate immune recognition. Mammalian Toll-like receptors play an essential role in innate immunity by recognizing conserved pathogen-associated molecular patterns and initiating the activation of NF-κB and other signaling pathways through the adapter protein, MyD88. Here we show that MyD88-deficient mice have a profound defect in the activation of antigen-specific T helper type 1 (TH1) but not TH2 immune responses. These results suggest that distinct pathways of the innate immune system control activation of the two effector arms of adaptive immunity.

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Figure 1: MyD88-deficient lymphocytes had no intrinsic defects in development and function.
Figure 2: Antigen-specific TH1 cell responses were impaired in MyD88-deficient mice.
Figure 3: Antigen-specific TH2-dependent immunoglobulin production was independent of MyD88.
Figure 4: Increased antigen-specific IL-13 production in MyD88-deficient lymph node cells.
Figure 5: Maturation of dendritic cells by mycobacteria requires MyD88.


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We thank C. A. Janeway and R. A. Flavell for the 1H3.1 TCR–transgenic and caspase-1–deficient mice, respectively. R. M. thanks C. A. Janeway for critical reading of the manuscript and continuous support. Supported by Howard Hughes Medical Institute, NIH (AI44220-01) and Searle (to R. M.) and by Deutsche Forschungsgemeinschaft (to M. S.).

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Correspondence to Ruslan Medzhitov.

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Schnare, M., Barton, G., Holt, A. et al. Toll-like receptors control activation of adaptive immune responses. Nat Immunol 2, 947–950 (2001).

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