Final answer:
MHC restriction refers to the requirement for T cells to recognize antigens presented on MHC molecules. MHC I presents antigens from inside the cell, while MHC II presents antigens from outside the cell. This recognition is crucial for the activation of the adaptive immune system.
Step-by-step explanation:
MHC restriction refers to the requirement for T cells to recognize antigens presented on major histocompatibility complex (MHC) molecules in order to initiate an immune response. There are two classes of MHC molecules, MHC I and MHC II. MHC I molecules are found on all nucleated cells and present antigens from inside the cell, while MHC II molecules are found on macrophages, dendritic cells, and B cells, and present antigens from outside the cell. The recognition of antigens by T cells through MHC restriction is crucial for the activation of the adaptive immune system.