PRECIPITATION: Antigen and Antibody Reaction
PRECIPITATION: When a soluble antigen combines with its antibody in presence of electrolytes (NaC1) at a suitable temperature and pH the antigen antibody complex forms insoluble precipitate.
Uses of Precipitation Reaction
(1) Identification of bacteria e.g., detection of group specific polysaccharides substance in streptococci in Lancefield grouping etc.
(2) Identification of antigenic component of bacteria in infected animal tissue. e.g., Bacillus anthracis (Ascoli test).
(3) Standardization of toxin and antitoxins.
(4) Demonstration of antibody in serum e.g., Kahn’s test for the diagnosis of syphilis.
(5) Medicolegal serology for detection of blood, serum etc
LATTICE HYPOTHESIS
Multivalent antigens combine with bivalent antibody in varying proportions, depending on antigen antibody ratio in reacting mixture. Precipitation results when large lattice is formed consisting of alternating antigen and antibody molecules. This is possible only in the zone of equivalence. In zone of antigen and antibody excess lattice does not enlarge as valency of antigen and antibody is fully satisfied.
Tags: bacillus, clostridium, deamination, spores, sporosarcina, tryptophan
Posted in Health |
You must be logged in to post a comment.