1: All viruses and some bacterial toxins affect cells by binding to receptors on our cells. 2: The second function is called optimization 3: Finally, bound antibodies activate a cascade called complement.
Antibodies are the primary defense against extra-cellular pathogens and they work in three main ways:
* Neutralization: When they bind to the pathogen or to the foreign substance the antibodies can block the association of the pathogen with its targets.
** Opsonization: The antibody upon binding to the pathogen or foreign substance may opsonize the material and facilitate its uptake and destruction by phagocytic cells.
*** Complement activation: The cascade of complement activation by the antibody may lead to lysis of certain bacteria and viruses. In addition, some components of the complement cascade opsonize pathogens and facilitate their uptake via complement receptors in phagocytic cells.
