Cross-presentation

Definition

Cross-presentation is a process where antigen-presenting cells (APCs) present extracellular antigens via MHC class I molecules to CD8+ T cells. This mechanism is crucial for initiating immune responses against pathogens that do not infect APCs directly.

5 Must Know Facts For Your Next Test

1. Cross-presentation enables the immune system to activate CD8+ cytotoxic T cells against viruses and tumors.
2. Dendritic cells are the primary APCs involved in cross-presentation.
3. This process involves pathways like the cytosolic pathway and vacuolar pathway to process antigens.
4. Cross-presentation can occur in both immature and mature dendritic cells.
5. Effective cross-presentation requires co-stimulatory signals alongside antigen presentation to fully activate CD8+ T cells.

Review Questions

• What types of cells primarily perform cross-presentation?
• How does cross-presentation differ from traditional antigen presentation?
• Why is cross-presentation important for the immune response against tumors?

Related terms

Major Histocompatibility Complex (MHC):

Protein molecules on cell surfaces that help the immune system recognize foreign substances.

Antigen-Presenting Cells (APCs):

Cells such as dendritic cells, macrophages, and B-cells that display antigens on their surface to T-cells.

CD8+ T Cells: A subtype of T cells that kill cancer cells, virus-infected cells, and sometimes other damaged or dysfunctional cells.