The exogenous pathway for antigen presentation on major histocompatibility complex class II and CD1 molecules

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Abstract

The endosomes and lysosomes of antigen-presenting cells host the processing and assembly reactions that result in the display of peptides on major histocompatibility complex (MHC) class II molecules and lipid-linked products on CD1 molecules. This environment is potentially hostile for T cell epitope and MHC class II survival, and the influence of regulators of protease activity and specialized chaperones that assist MHC class II assembly is crucial. At present, evidence indicates that individual proteases make both constructive and destructive contributions to antigen processing for MHC class II presentation to CD4 T cells. Some features of CD1 antigen capture within the endocytic pathway are also discussed.

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Figure 1: Ii processing proceeds in a C-terminal–to–N-terminal direction.
Figure 2: Alternative scenarios and fates of T cell epitopes during antigen processing.
Figure 3: Multiple influences on protease activity in the endocytic compartment.

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Supported by The Wellcome Trust, Medical Research Council and European Union.

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Correspondence to Colin Watts.

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Watts, C. The exogenous pathway for antigen presentation on major histocompatibility complex class II and CD1 molecules. Nat Immunol 5, 685–692 (2004) doi:10.1038/ni1088

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