The production of antibody by B cells of the immune system in response to the presence of a foreign antigen. See antibody-mediated immune response.

The part of the immune response mediated by antibody present in extracellular fluids, such as the cell-free fractions of blood (serum or plasma), lymph and tissue fluids. Humoral immunity is the main line of defense against extracellular bacteria but it can also contribute to protection against some viruses and some forms of cancer.

The immune response that is mediated by B-cells and involves production of antibodies. Humoral immunity (also known as TH-1 immune response) is associated with the production of the cytokines interleukin-4 and interleukin-10.