AAMC FL Practice Exam

Which type of immunity do B cells contribute to?

1. Cell-mediated immunity

2. Innate immunity

3. Humoral immunity

4. Adaptive immunity

The correct answer is: Humoral immunity

B cells are a crucial component of the immune system that specifically contribute to humoral immunity. This type of immunity involves the production of antibodies, which are proteins that can specifically recognize and bind to antigens (foreign substances) such as viruses and bacteria. When B cells encounter an antigen that matches their unique receptors, they become activated, proliferate, and differentiate into plasma cells. These plasma cells then produce large quantities of antibodies that circulate in the bloodstream, targeting the specific pathogens. Humoral immunity is distinct from cell-mediated immunity, which involves T cells and does not primarily rely on antibodies. While B cells are part of the adaptive immune response, they specifically differentiate the functional role they play as producers of antibodies—making humoral immunity the most precise answer for the contribution of B cells within the context given. Innate immunity, on the other hand, refers to the body's initial, non-specific defense mechanisms that are present from birth, such as physical barriers (skin) and various immune cells like macrophages and natural killer cells, which do not include B cells. Adaptive immunity encompasses both humoral and cell-mediated responses but does not specify the function of B cells specifically, which is why humoral immunity is the most accurate choice.