1. In vivo, the combination of antibody and antigen can play a direct role, such as antitoxin can neutralize exotoxin, virus neutralizing antibody can prevent virus from infecting target cells, and secretory IgA can inhibit bacteria from adhering to host cells.
2. In vitro, agglutination and precipitation may occur after antibody binds to antigen. Immunoglobulin can activate complement; It binds to Fc receptor on the cell surface, thus showing different biological effects, such as conditioned action, antibody-dependent cell-mediated cytotoxicity and type I hypersensitivity.
3. Through placenta and mucosa, IgG is the only IgG type that can pass through placenta in human body. The transmission of maternal IgG to fetus through placenta is an important natural passive immunity, which is of great significance to neonatal anti-infection.
4. Secretory IgA can pass through the mucosa of digestive tract and respiratory tract, which is the main factor of local immunity of body mucosa. In addition, antibodies have positive and negative regulatory effects on immune response.
Efficacy:
1. Immunoglobulin can be divided into antibody and membrane immunoglobulin.
2. The main function of antibody is to specifically bind antigen.
3. Membrane immunoglobulin is an antigen receptor on B cell membrane, which can specifically recognize antigen molecules.
Extended data:
Antibody is a kind of globulin with immune function, which is synthesized and secreted by B cells after immune cells are activated by antigens and differentiated into plasma cells. Antibody is the concept of biological function, while immunoglobulin is the concept of chemical structure.
Immunoglobulin (Ig) refers to globulin with antibody (Ab) activity or chemical structure, which is similar to antibody molecule. Immunoglobulin is a tetrapeptide chain structure, which is composed of two identical light chains and two identical heavy chains connected by disulfide bonds between chains. Immunoglobulin is divided into five categories, namely immunoglobulin G(IgG), immunoglobulin A(IgA), immunoglobulin M(IgM), immunoglobulin D(IgD) and immunoglobulin E(IgE).
References:
Immunoglobulin-Baidu Encyclopedia