Humoral and Cellular Immunity

Abstract

When the adaptive immune system is activated by the innate immune system, the humoral immune response (also: antibody-mediated immune response) triggers specific B cells to develop into plasma cells. These plasma cells then secrete large amounts of antibodies. Antibodies circulate in the lymph and the blood streams. (Hence the name: humoral immunity. Humoral comes from the Greek chymos, a key concept in ancient Greek medicine. In this view, people were made out of four fluids: blood, black bile, yellow bile and mucus (phlegma). Being healthy meant that the four humors were balanced. Having too much of a humor meant unbalance resulting in illness.) The more general term for antibody is immunoglobulin, a group of proteins. There are five different antibody classes: IgG, IgM, IgA, IgE and IgD.