Final answer:
T cells can directly kill infected cells, which is the process they engage in, unlike B cells that produce antibodies. T cells are central to cell-mediated immunity, which involves the destruction of infected cells and the orchestration of the immune response through cytokine release.
Step-by-step explanation:
The T cells engage in the direct killing of infected cells but do not produce antibodies, activate macrophages, or phagocytose pathogens.
B cells help fight infections by producing antibodies that identify and neutralize pathogens in the blood and lymph. An antibody is a protein that specifically binds to a unique part of a pathogen called an antigen. This binding can lead to the pathogen's destruction or interference with its function. On the other hand, killer T cells perform cell-mediated immunity by destroying infected body cells through the recognition of pathogen-derived antigens presented on these cells' surfaces. Helper T cells, which can be Th1 or Th2, play a pivotal role in the immune response. Th1 cells secrete cytokines that enhance macrophage activity, and Th2 cells induce B cells to become antibody-secreting plasma cells. However, unlike B cells, most T cells do not recognize native unprocessed antigens, do not require the participation of MHC molecules in antigen recognition, and do not produce antibodies.
Different T cell types perform various functions in the immune response, but they do not engage in antibody production like B cells. The processes that T cells are involved in include:
Direct killing of infected cells: Killer T cells identify and destroy cells infected with pathogens.
Activation of macrophages: T helper cells release cytokines that enhance the activity of macrophages.
Phagocytosis of pathogens: Certain T cells, such as dendritic cells, can phagocytose or engulf pathogens.
Therefore, the correct answer is 1) Antibody production.