Final answer:
CD8+ cytotoxic T cells have the CD8 receptor that recognizes peptide antigens presented by major histocompatibility complex class I (MHC I) molecules, which is essential for their activation and function in the immune response.
Step-by-step explanation:
T cells, specifically CD8+ cytotoxic T cells (Tc cells), have the CD8 receptor on their surface, which recognizes peptide antigens bound to major histocompatibility complex class I (MHC I) proteins. The interaction between the CD8 receptor and the MHC I molecules on antigen-presenting cells (APCs) is crucial for the activation of CD8+ T cells, leading them to become cytotoxic T lymphocytes (CTLs).
These CTLs play a vital role in the immune system by directly killing infected cells through apoptosis. Additionally, they secrete cytokines to enhance the immune response against pathogens. On the other hand, CD4+ T cells interact with MHC II molecules to become helper T cells, which assist other immune cells in responding to the presence of a pathogen.