Principle of antigen-antibody reaction

Both antigens and antibodies are important material components in the human body, and many functional responses in the human body are carried out through the combination of antigens and antibodies. However, people who are in frequent contact with medicine should be very clear about the working principles of antigens and antibodies. But for ordinary people, they have no idea what antigens and antibodies are, let alone the principles of antigen and antibody reactions. Today I will introduce to you the reaction principles of antigens and antibodies.

Antigen-antibody reaction refers to the specific binding reaction between an antigen and its corresponding antibody. This reaction can take place both inside and outside the body. The process of antigen-antibody reaction goes through a series of chemical and physical changes, including two stages: antigen-antibody specific binding and nonspecific aggregation, as well as the change from hydrophilic colloid to hydrophobic colloid.

Reaction characteristics

There are three main characteristics of antigen-antibody reactions: specificity, proportionality, and reversibility.

Specificity is the most important feature of antigen-antibody reaction, which is determined by the complementarity of the spatial structure between the antigenic determinant and the hypervariable region of the antibody molecule. This high specificity has been effectively applied in the diagnosis and prevention of infectious diseases. With the development and progress of immunological technology, it will be more deeply and widely used in the fields of medicine and biology, such as diagnosis and specific treatment of tumors.

Proportionality means that the visible reaction between antigen and antibody must follow a certain quantitative ratio relationship. A visible reaction will only occur when the concentration ratio of the two is appropriate. When the antigen-antibody ratio is equal or there is a slight excess of antigen, the reaction is most thorough and the immune complex precipitate is the most and largest. When the antigen-antibody ratio exceeds this range, the reaction rate and the amount of precipitation will decrease rapidly or even no antigen-antibody reaction will occur.

Reversibility refers to the property that after antigen and antibody combine to form a complex, they can dissociate and return to antigen and antibody under certain conditions. Since the antigen-antibody reaction is a non-covalent bond on the surface of molecules, the complex formed is not strong and can dissociate at any time. After dissociation, the antigen-antibody still maintains its original physical and chemical characteristics and biological activity.

Reaction Principle

Antibodies can specifically recognize and bind to corresponding antigens. This binding can also occur in vitro.

Characterization is the basis of many immunoassays. The interaction between antigen and antibody is non-covalent and reversible, and its characteristics conform to the basic principles of many chemical reactions. However, due to the structural characteristics of antibody molecules and the diversity of antigen molecular structures, the antigen-antibody binding reaction is complex[1-3].