Final answer:
TH1 cells are involved in the adaptive immune response to intracellular bacteria and protozoa, enhancing the capability of macrophages to destroy these pathogens.
Step-by-step explanation:
For intracellular bacteria and protozoa, the type of cell used in the adaptive immune response is TH1 cells. These cells are key players in the defense against intracellular pathogens like Mycobacterium tuberculosis.
When an infection by such pathogens occurs, macrophages present antigens to naïve T cells and stimulate them to become TH1 cells. Then, the TH1 cells secrete cytokines that enhance the macrophage's ability to digest and destroy the pathogen. On the other hand, TH2 cells are involved in stimulating naïve B cells to produce antibodies, which is a response more suited to extracellular pathogens.