Antigen-Antibody Precipitation Reaction

• Precipitation in solution occurs when antibodies react with antigens.
• This reaction results in the formation of an antigen-antibody complex that loses its solubility and precipitates.
• For the precipitation reaction to occur, the formation of a three-dimensional network is necessary.
• The amount of Ag and Ac present must be in an optimal ratio for the formation of the precipitate.
• Additional addition of Ag will reduce the amount of precipitate.
• The maximum amount of precipitate is obtained when there is a between Ag and Ac the ideal ratio – the equivalence zone.
• In cases where there is excess of antibodies, large and soluble complexes are formed.
• In cases where there is excess of antigen, a minimal amount of precipitate is formed.
• Significant amounts of Ag-Ac complexes are present in the supernatant in cases where antibodies are excess.
• Nephelometry is used to quantitate proteins from a solution in which antibodies are present in excess.
• IgG, IgA, IgM, complement system factors (C3, C4, factor B), and C-reactive protein all play a role in the precipitation reaction.

Test your knowledge about the precipitation reaction that occurs when antibodies react with antigens, resulting in the formation of an antigen-antibody complex. Understand the optimal ratio required for precipitation and the role of various proteins in this reaction.