Which immune response is mediated by antibodies?

Humoral immunity is specifically mediated by antibodies. This branch of the immune system involves B cells, which are a type of lymphocyte that produce antibodies in response to antigens. When these B cells encounter an antigen, they differentiate into plasma cells that secrete antibodies. These antibodies can bind to specific antigens, neutralizing pathogens, marking them for destruction, or preventing their ability to infect cells. This response is crucial for defending against extracellular pathogens, such as bacteria and toxins, that are present in body fluids.

Cell-mediated immunity, on the other hand, primarily involves T cells and does not rely on antibodies for its effects. Instead, T cells directly attack infected cells or help coordinate the immune response without the action of antibodies. Innate immunity refers to the body’s first line of defense, which includes physical barriers and immune cells that respond to pathogens in a non-specific manner, rather than the specific action of antibodies. Passive immunity involves the transfer of antibodies from one individual to another, such as from mother to infant, but does not involve the direct production of antibodies by the recipient's immune system.