What is Cell-Mediated Immunity?
During a cell-mediated immune response (also known as a type 1 response), B cells—and antibody production—are not activated. Instead, a range of other cells, which are capable of either directly or indirectly killing intracellular bacteria and infected host cells, are activated.
These include phagocytes such as macrophages, as well as natural killer cells, which are capable of directly killing bacterial cells as well as infected host cells.
As the adaptive immune response kicks into gear, type 1 helper T cells are activated, and these help control and direct the immune response to ensure it is capable of eliminating the pathogen causing the infection.
In addition, cytotoxic T lymphocytes are activated. These are antigen-specific cells which, once activated, are capable of killing host cells which have been infected with intracellular pathogens.