Antigen antibody interaction ppt

Antigen-antibody interaction, or antigen-antibody reaction, is a specific chemical interaction between antibodies produced by B cells of the white blood cells and antigens during immune reaction. It is the fundamental reaction in the body by which the body is protected from complex foreign molecules, such as pathogens and their chemical toxins. In the blood, the antigens are specifically and with high affinity bound by antibodies to form an antigen-antibody complex. The immune complex is then transported to cellular systems where it can be destroyed or deactivated.

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\( \newcommand\) • • • Precipitation reactions are serological assays for the detection of immunoglobulin levels from the serum of a patient with infection. Key Points • Precipitation assays are performed in semi-solid media such as agar or agarose where antibodies and antigens can diffuse toward one another and form a visible line of precipitation. • There are several precipitation methods applied in the diagnostic laboratory. These include single, double, and electroimmunodiffusion. • The most widely used gold standard precipitation methods are Ouchterlony test and Mancini test. Key Terms • precipitin: Any antibody which reacts with an antigen to form a precipitate. Precipitation reactions are based on the interaction of antibodies and antigens. They are based on two soluble reactants that come together to make one insoluble product, the precipitate. These reactions depend on the formation of lattices (cross-links) when antigen and antibody exist in optimal proportions. Excess of either component reduces lattice formation and subsequent precipitation. Precipitation reactions differ from agglutination reactions in the size and solubility of the antigen and sensitivity. Antigens are soluble molecules and larger in size in precipitation reactions. There are several precipitation methods applied in clinical laboratory for the diagnosis of disease. These can be performed in semisolid media such as agar or agarose, or non-gel support media such as cellulose acetate. Figure: Pr...

August 24, 2021 Elementary Immunology Antigen and Antibody react with each other in three stages: Primary stage Secondary stage Tertiary stage Combination of antigen + antibody 1. Agglutination 1. Opsonization 2. Precipitation 2. Lysis 3. Complement activation 4. Neutralization 5. Blocking of antigen sites Primary Stage In the primary stage, a combination of antigen and antibody gives rise to antigen and antibody complex formation (Ag + Ab). Combination of Ag and Ab Secondary Stage Agglutination • Definition: • Agglutination is the visible form of aggregation of antigen and antibody, with the formation of the network in which antigen particle (molecule) alternate with the antibody molecule. • The ability of the particular antibody to attach with the antigen is its specificity. • This is the property of the Fab portion called combining sites; a cleft is formed by the hypervariable of heavy and light chains. The hypervariable area is called the Fab portion. • This specificity lies in the Fc portion of the antibody. • Examples of the carrier are: • In the case of soluble antigens, latex particles or colloidal charcoal are needed. • RBCs can be used as a biological carrier. • Bacteria possess an antigen that reacts with the antibody. • Quality of the agglutination depends upon: • Time of incubation of the patient serum, which contains antibody. • The condition where the tests are run like pH and protein concentration. • Amount the antigen conjugated with the carrier. • The ant...