Final answer:
Helper T cells enhance the intracellular killing of extracellular pathogens by macrophages and neutrophils through direct contact and secretion of cytokines.
Step-by-step explanation:
Helper T cells, also known as TH1 cells, enhance the intracellular killing of extracellular pathogens by macrophages and neutrophils through direct contact and secretion of cytokines that activate these immune cells. When helper T cells are activated, they release specific cytokines that stimulate macrophages and neutrophils to become more effective in killing intracellular bacteria. This enhanced immune response helps to eliminate the invading pathogens.