What is cross presentation of exogenous antigens?
Cross-presentation is the ability of certain professional antigen-presenting cells (mostly dendritic cells) to take up, process and present extracellular antigens with MHC class I molecules to CD8 T cells (cytotoxic T cells).
What causes cross presentation?
Dendritic cells (DCs) present foreign antigen in major histocompatibility complex (MHC) class I molecules to cytotoxic T cells in a process called cross-presentation. Thus, NOX2 induces antigen release from endosomes for cross-presentation by direct oxidation of endosomal lipids.
How are exogenous antigens processed and presented?
Exogenous proteins, however, are primarily presented by MHC-II molecules. Antigens are internalized by several pathways, including phagocytosis, macropinocytosis, and endocytosis, and eventually traffic to a mature or late endosomal compartment where they are processed and loaded onto MHC-II molecules.
What is exogenous antigen?
Definition. Antigen that enters the body of the organism from the outside, e.g. through inhalation, ingestion, or injection. Supplement. Exogenous antigens include particles considered foreign within the organism.
What is the function of cross-presentation?
Antigen cross-presentation enables dendritic cells (DCs) to present extracellular antigens on major histocompatibility complex (MHC) I molecules, a process that plays an important role in the induction of immune responses against viruses and tumors and in the induction of peripheral tolerance.
What happens during antigen presentation?
Most often, antigen processing refers to the generation of antigenic peptides from proteins. Antigen presentation refers to the binding of these peptides to MHC molecules and the positioning of the resulting pMHC complexes on a host cell surface so that they can be inspected by T cells.
What is the function of cross presentation?
Where does cross presentation occur?
Cross presentation occurs when an antigen made outside the APC is internalized by endocytosis or phagocytosis, and instead of complexing with class II MHC, it is routed to a compartment containing class I MHC.
What is the difference between endogenous and exogenous antigens?
Endogenous antigens are antigens found within the cytosol of human cells such as viral proteins, proteins from intracellular bacteria, and tumor antigens. Exogenous antigens are antigens that enter from outside the body, such as bacteria, fungi, protozoa, and free viruses.
What is the difference between endogenous and exogenous pathway?
(a) Endogenous pathway shows viral antigens that enter the host cells by the intracellular route. (b) Exogenous pathway shows antigens that enter the antigen presenting cells (APCs) via the extracellular route which results in internalization of the antigens in the endosomes.
What is the difference between endogenous and exogenous antigen?
What is the exogenous pathway?
The exogenous pathway is utilized by specialized antigen-presenting cells to present peptides derived from proteins that the cell has endocytosed. The peptides are presented on MHC class II molecules. This fuses with a late endosome containing the endocytosed, degraded proteins.
How are exogenous antigens presented to the cell?
Cross-presentation is the process by which exogenous antigens captured by phagocytic antigen-presenting cells are processed and presented onto MHC-I molecules (1, 2). Early evidence supports the notion that cell-associated antigens are a physiological substrate for cross-presentation.
How are antigens cross presentation in dendritic cells?
Dendritic cells utilize distinct and overlapping pathways for cross-presentation. Phagosomes acquire cytosolic and ER-derived proteins for MHC-I loading of peptides. In order to get recognized by CD8 T cells, most cells present peptides from endogenously expressed self or foreign proteins on MHC class I molecules.
How is cross presentation of antigens an evolutionary response?
Heath and Carbone have proposed that the cross-presentation is an evolutionary response to evasion mechanisms associated with the direct infection of DCs by viruses (e.g., the inhibition of direct presentation or migratory behavior) ( 7 ).
How are antigens presented on the MHC I?
However, specialized antigen-presenting cells, such as DCs and macrophages, can present exogenous antigen on MHC-I in a process called cross-presentation. This pathway plays key roles in antimicrobial and antitumor immunity, and also immune tolerance.