Final answer:
Cytotoxic T cells with CD8 markers recognize MHCI/antigen complexes, targeting infected cells, while Helper and Regulatory T cells with CD4 markers recognize MHCII/antigen complexes, working with APCs for immune response regulation.
Step-by-step explanation:
T Cells and Antigen Recognition
T cells recognize antigens with a specialized structure on their surface called a T-cell receptor (TCR). The type of T cell that recognizes MHCI/antigen is known as a cytotoxic T cell, identifiable by the presence of a CD8 marker. These cells are primarily responsible for recognizing and destroying cells infected by intracellular pathogens, such as viruses, that present peptides with MHCI.
On the other hand, MHCII/antigen complexes are recognized by helper T cells and regulatory T cells, which have the CD4 marker. These cells interact with antigen-presenting cells (APCs) such as macrophages, dendritic cells, and B cells that present antigens using MHCII. Helper T cells are crucial for activating B cells and other immune cells, while regulatory T cells help to maintain immune tolerance and prevent autoimmune responses.