Cell mediated immunity is carried out by………….. while humoral immunity is mainly carried out by………………..
a. B cells/T cells
b. Epitopes/Antigens
c. T cells/B cells
d. Antibodies/Antigens
e. Antibodies/Phagocytes
The correct answer and explanation is :
Correct Answer: c. T cells/B cells
Explanation:
The immune system protects the body against pathogens using two main strategies: cell-mediated immunity and humoral immunity. These are the two branches of the adaptive immune response, each involving different types of lymphocytes (white blood cells).
Cell-Mediated Immunity
Cell-mediated immunity is primarily carried out by T cells (T lymphocytes). These cells are produced in the bone marrow but mature in the thymus, hence the name “T” cells. This form of immunity does not rely on antibodies but rather involves direct action by T cells to combat infected or abnormal cells.
There are several types of T cells:
- Cytotoxic T cells (CD8⁺) destroy virus-infected cells, tumor cells, and damaged cells.
- Helper T cells (CD4⁺) assist other immune cells by releasing cytokines that enhance the immune response.
- Regulatory T cells help maintain tolerance and prevent autoimmune responses.
This type of immunity is especially important in fighting intracellular pathogens, such as viruses, some bacteria, and in destroying cancerous or transplanted cells.
Humoral Immunity
Humoral immunity is mediated by B cells (B lymphocytes), which are produced and mature in the bone marrow. When B cells encounter an antigen, they can differentiate into plasma cells that secrete antibodies (also called immunoglobulins).
Antibodies circulate in body fluids (“humors” like blood and lymph), binding specifically to antigens on pathogens to neutralize them or mark them for destruction by other immune cells. This pathway is crucial for defending against extracellular pathogens, such as bacteria and viruses that are not inside host cells.
In summary, T cells are central to cell-mediated immunity, dealing with infected or altered host cells, while B cells are essential for humoral immunity, producing antibodies to neutralize pathogens in body fluids.