What are the biological effects of antibody binding antigen

Solution

Antigen-antibody response constitutes a basic immunological reaction and describes a specific response between antigen and antibody. In vitro reactions refers to the Antigen-antibody reactions occurring outside host. Antigen-antibody reactions in vitro are known as serological reactions.

The primary stage is the initial interaction between the two, without any visible effects. This reaction is rapid, and reversible, the combination between antigen and antibody molecules being effected by the weaker intermolecular forces rather than by the firmer covalent bonding. In most instances, but not all, the primary stage is followed by the secondary stage leading to demonstrable events such as precipitation, agglutination, lysis of cells, killing of live antigens, neutralization of toxins and other biologically active antigens, fixation of complement, immobilization of motile organisms and enhancement of phagocytosis. Thus in such reactions a single antibody can cause precipitation, agglutination and most of the other serological reactions, an antigen can stimulate the production of different classes of immunoglobulin which differ in their reaction capacities as well as in other properties.