Humoral immunity or humoural immunity is the aspect of immunity that is mediated by macromolecules found in extracellular fluids such as secreted antibodies , complement proteins , and certain antimicrobial peptides . Humoral immunity is so named because it involves substances found in the humors , or body fluids . It contrasts with cell-mediated immunity . Its aspects involving antibodies are often called antibody-mediated immunity .
Cell mediated immune response is carried out by the T-cells or T lymphocytes (Fig. 11). So, it is also called T-cell immunity. This type of immune response is to defend against pathogens that may invade host cells. The surface of the T-cell has receptor molecule that can bind with antigens. These receptor molecules are made of a variable unit similar to the variable portion of the humoral antibody. A single T-cell has about 100,000 receptor sites.