Activated CD8 T cells are able to destroy any cell type harboring replicating pathogens because pathogen-derived peptides are loaded onto MHC class I molecules present in endosomes of all nucleated cell types. MHC class I molecules, which present peptides from intracellular pathogens, are expressed ubiquitously on most nucleated cells and allow CD8 T cells to recognize and kill those cells containing pathogens.

1. Which of the following characteristics enables activated CD8 T cells to destroy any cell type
harboring viable and replicating pathogens such as viruses? Cells containing intracellular
pathogens upregulate co-stimulatory molecules to promote T cell activation. CD8 T cells enable
macrophages to kill intracellular pathogens. Pathogen-derived peptides are loaded onto MHC
class I molecules in endosomes present in cell types. MHC class II molecules are expressed
ubiquitously by most nucleated cells. MHC class I molecules are expressed ubiquitously by most
nucleated cells.