Final answer:
Cell-mediated immunity involves T cells and is essential for targeting intracellular pathogens. It includes cells such as helper T cells, cytotoxic T lymphocytes, and molecules such as antigens and MHC proteins. This is distinct from humoral immunity, which involves B cells and antibodies.
Step-by-step explanation:
Understanding Cell-Mediated Immunity
Cell-mediated immunity is a type of immune response that primarily involves T lymphocytes, also known as T cells. This adaptive immune mechanism is essential for targeting and eliminating intracellular pathogens, such as viruses, as well as some cancer cells. It differs from the humoral immune response, which is mediated by B lymphocytes (B cells) producing antibodies. To comprehensively label a diagram representing cell-mediated immunity, one would identify cells such as helper T cells, cytotoxic T lymphocytes (Tc), and regulatory T cells, as well as molecules like antigens, cytokines, and major histocompatibility complex (MHC) proteins.
MHC I molecules present antigens on the surface of all nucleated cells to cytotoxic T cells. These T cells are responsible for killing infected cells. On the other hand, MHC II molecules are expressed on antigen-presenting cells, such as macrophages, dendritic cells, and B cells, and are involved in the activation of T cells.
Antigens are substances that can elicit an immune response, and are often parts of pathogens like bacteria or viruses. T cells recognize these antigens presented by MHC molecules and initiate an immune response. Antibodies, which are not part of cell-mediated immunity but rather the humoral response, are produced by B cells and target pathogens found in body fluids. Vaccination can act by exposing the immune system to these antigens, prompting the creation of memory cells that allow for a quicker immune response upon subsequent exposures.