Final answer:
Cytotoxic T cells are activated by antigen presentation with MHC I and interaction with the CD8 receptor, requiring cytokine stimulation for proliferation and differentiation into effector cells or memory cells.
Step-by-step explanation:
The activation of cytotoxic T cells entails a series of steps that begin when the T-cell receptor (TCR) on the cytotoxic T cell recognizes a pathogen epitope presented by MHC I on an antigen-presenting cell (APC). Co-recognition of the epitope and self-antigen triggers the cytotoxic T cell and stimulates the release of cytokines that lead to cell activation. These cytokines are often secreted by TH1 cells activated by the same epitope. Upon activation, cytotoxic T cells proliferate and differentiate into either effector cytotoxic T cells, which target and kill infected cells, or memory cells that respond to future exposures.
The activation of cytotoxic T cells can also occur with less efficacy and longevity in the absence of co-stimulation from TH1 cells, further underscoring the importance of cytokines in the response to pathogens.
Following activation, these effector cells execute the role of killing infected cells through mechanisms involving the secretion of proteins such as perforin and granzymes, leading to apoptosis of the target cells.