Biology Reference
In-Depth Information
T A B L E 11.1. Unique Features of DC Defining
Them as Professional APC
Unique DC features
In vivo localization
Antigen capture
Antigen processing
Speci®c migratory ability
Antigen presentation
Costimulatory molecules
Activation of naive T cells
sentinels against invading pathogens (Fig. 11.1). Upon pathogen in®ltration,
resident DC, as well as DC precursors from blood, migrate speci®cally to the
site of in¯ammation and sample the pathogens. Captured pathogens are e½-
ciently processed to an array of peptides for presentation at the cell surface on
MHC class I and II molecules. DC migrate after pathogen capture to lymphoid
tissues to present foreign peptides to T cells and activate antigen-speci®c T cells.
DC are such e½cient APC because they exist in two functionally di¨erent
forms, generally classi®ed immature and mature. Both forms have unique
abilities that are necessary for their di¨erent functions. Immature DC are
highly e½cient at antigen capture, internalization, and processing, but poor at
Figure 11.1. DC capture foreign pathogens, migrate, and activate T cells. DC precursors emi-
grate from the blood into the peripheral tissues where they di¨erentiate into immature DC that
patrol these tissues. Immature DC migrate toward sites of pathogen entry and capture antigens,
after which they mature and migrate through the lymphatics into the lymphoid compartments. At
these sites, the mature DC interact with resting T cells, resulting in antigen-speci®c T-cell activation
and thus the initiation of an e½cient immune response.
