What type of immune response is primarily mediated by antibodies?

• A. Cell-mediated immunity
• B. Humoral immunity
• C. Adaptive immunity
• D. Innate immunity

Answer: (B)

The immune response that is primarily mediated by antibodies is humoral immunity. This type of immunity involves B cells, which are a class of lymphocytes, that produce antibodies in response to specific antigens. Antibodies are proteins that can bind to antigens, neutralizing pathogens, marking them for destruction by other immune cells, or preventing their entry into cells.

Humoral immunity is vital for defending against extracellular pathogens such as bacteria and viruses present in body fluids. The antibodies produced during humoral responses can provide long-lasting protection through memory B cells, which can rapidly produce antibodies upon re-exposure to the same antigen.

In the context of the other types of immunity: cell-mediated immunity is primarily dependent on T cells and involves the direct destruction of infected cells; adaptive immunity encompasses both humoral and cell-mediated responses but does not specifically focus on the role of antibodies; and innate immunity is the body's first line of defense that provides rapid, non-specific responses without the memory characteristic of adaptive responses. Thus, the specificity of humoral immunity for antibody production clearly demonstrates why this is the correct answer to the question.