Final answer:
The MHC-peptide complex is recognized by T-cell receptors (TCR) on T cells, leading to cellular immune responses including the destruction of infected host cells. This process is integral to the body's ability to distinguish self from non-self and orchestrate targeted immune responses against pathogens.
Step-by-step explanation:
The MHC-peptide complex is recognized by T-cell receptors (TCR) on T cells. This recognition is critical for the activation of T cells, which is a central mechanism of the adaptive immune system. The complex involves antigen fragments that are enzymatically cleaved, associated with MHC molecules, presented on the surface of antigen-presenting cells, and then physically recognized by TCRs. This antigen presentation plays a pivotal role in differentiating self from non-self and in targeting cells infected with intracellular pathogens like viruses for destruction.
Different classes of MHC molecules, namely MHC class I and MHC class II, have distinct functions. MHC class I is present on all nucleated cells and primarily presents self-antigens as well as foreign antigens from intracellular pathogens, while MHC class II presents antigens that have been internalized and processed by antigen-presenting cells like macrophages and dendritic cells. The interaction between the MHC-peptide complex and TCR leads to various immune responses, including the destruction of cells harboring intracellular pathogens, and is a key step in the immune system's ability to fight infections.