Naive CD8⁺ T cells require signals in addition to T cell receptor recognition of peptide-MHC to become activated and differentiate into cytolytic T cells. These signals are called costimulatory signals and are provided by professional antigen-presenting cells (APCs), such as dendritic cells. If a virus infects epithelial cells in the respiratory tract but does not infect professional APCs, what process ensures that naive T cells specific for viral antigens will become activated?
A)Cross-reactivity, whereby the naive CD8⁺ T cell recognizes a self antigen that is structurally similar to a viral antigen presented by dendritic cells
B)Crossover, whereby part of the viral genome is exchanged with part of one chromosome of the host
C)Crosstalk, whereby signals generated by the virus binding to class I MHC molecules intersect with T cell receptor signaling pathways
D)Cross-presentation, whereby infected epithelial cells are captured by dendritic cells, and the viral proteins originally synthesized in the epithelial cells are processed and presented in association with class I MHC molecules on the dendritic cell
E)Cross-dressing, whereby viral infection of the epithelial cell stimulates the expression of surface molecules that are typically found only on dendritic cells

Question

Quizplus · Accepted Answer

Cross-presentation (or cross-priming) is the phenomenon by which a protein antigen made within one cell is processed and presented by the class I MHC pathway of a separate professional antigen-presenting cell (APC). Cross-presentation requires that the protein antigen from one cell be internalized from the extracellular milieu into the APC to gain access to the cytoplasm of the APC. Crossover and crosstalk are terms referring to genetic and signaling phenomena, which are not accurately described in the question. Cross-dressing is not a term used in immunology.

Naive CD8⁺ T Cells Require Signals in Addition to T