The humoral immune response is one of two main arms of the immune system. In this response, the immune system triggers specific B cells to proliferate and secrete large amounts of their specific antibodies. These antibodies can then combat a particular microorganism or virus and thereby stop an infection.
The humoral immune response has an activation phase and effector phase. During the activation phase, helper T (TH) cells become activated against a particular antigen. In the effector phase, activated TH cells trigger specific B cells to proliferate and release antibodies. These antibodies then bind to the invader and fight the infection.
By the end of the humoral response, the immune system has activated specific B cells, which produce and release large amounts of their specific antibodies. Of the millions of different B cells produced by the immune system, only those that can recognize the invader are activated. This specificity prevents the body from making all types of antibodies possible (which would very likely harm the body, in addition to being energetically costly).
Antibodies defend the body in a number of ways. For example, if the antigen is a toxin or a virus, the binding of antibodies to the antigens isolates the antigens, preventing them from contacting and harming cells of the body. Additionally, antigens that are coated with antibodies are easily recognized by macrophages, engulfed, and digested. Antibodies also stimulate the complement system, which consists of a group of proteins that can poke holes in the cell walls of bacteria.
Textbook Reference: Concept 39.4 The Adaptive Humoral Immune Response Involves Specific Antibodies