Agglutination vs Precipitation- Major Differences
Basis for Comparison |
Agglutination |
Precipitation |
Definition |
Agglutination is the process of
clumping of antigens with their respective antibodies. |
Precipitation is a process where
soluble antigens bind with their specific antibody at an optimum temperature
and pH, resulting in the formation of an insoluble precipitate. |
Antigen size |
The antigen involved in
agglutination is comparatively smaller. |
The antigen involved in
precipitation is comparatively larger. |
Solubility |
Insoluble antigens are used for
agglutination. |
Soluble antigens are used for
precipitation. |
Sensitivity |
Agglutination reactions are more
sensitive than precipitation reactions. |
Precipitation reactions are less
sensitive than agglutination reactions. |
Principle |
Agglutination is based on the
principle of the clumping of particles. |
Precipitation is based on the
principle of the formation of lattices (cross-linkages). |
Reactions involved |
Agglutination involves
complex-forming chemical reactions. |
Precipitation involves chemical
reactions between ions and salt molecules. |
Media |
No gel matrix is required for
agglutination. |
A liquid or semi-solid matrix is
required for precipitation. |
Resulting compound |
Agglutination results in the
formation of agglutinates. |
Precipitation results in the
formation of precipitates. |
Nature of the complex formed |
The agglutinins usually settle
towards the bottom of the container. |
The precipitins might either
remain suspended or settle down towards the bottom. In flocculation, the
flocculants float on the surface of the liquid matrix. |
Nature of reactants |
The starting molecules in
agglutination are particles. |
The starting molecules in
precipitation are ions. |
Requirements |
Agglutination reactions are
surface reactions, and thus the surface of the antigens must be exposed for
the antibody to bind and form visible clumps. |
The concentration of antigen and
antibody should be equal. Any change in this equivalence prevents the
formation of precipitins. |
Reaction time |
Agglutination reactions might
require minutes to hours for completion. |
Precipitation reactions might
occur in hours to days. |
Appearance |
The end products of agglutination
reaction appear as large visible aggregates. |
The end products of precipitation
reaction appear as large insoluble visible aggregates. |
Applications |
Agglutination reactions are useful
in blood grouping. |
Precipitation reactions are useful
in quantitative analysis and pigment formation. |
Agglutination is the process of clumping of antigens
with their respective antibodies.
·
Agglutination reactions are used to particulate test antigens that
are usually conjugated to a carrier.
·
The carrier can either be artificial (such as latex or charcoal
particles) or biological (such as red blood cells).
·
The agglutination process involving red blood cells is termed
hemagglutination, and the process with white blood cells is termed
leukoagglutination.
·
These conjugated particles then react with the patient’s serum
which might or might not contain antibodies.
·
The result of this test can be collected based on the observation
of clumps resulting from that antigen-antibody complex formation.
·
The sensitivity and accuracy of the result depend on a number of
factors like the duration of incubation with the antibody, amount and strength
of the antigen conjugated to the carrier, and test conditions like the pH and
protein concentration.
·
Different forms of agglutination are used in diagnostic tests
which include latex agglutination, flocculation tests, direct bacterial
agglutination, and hemagglutination.
·
Because the process is quick and straightforward, these diagnostic
tests are preferred over other sophisticated tests.
·
Agglutination has been used for the detection of antigens in
bacteria which ultimately helps in the identification of those bacteria.
·
A modified and more sensitive technique associated with
agglutination is agglutination-PCR.
·
In this technique, the antibodies bind and agglutinate with
antigen-DNA conjugates which enables the DNA strands to ligate with the
antibodies.
·
The agglutination formed is then used to quantify the DNA strands
by q-PCR.
Precipitation is a process where soluble antigens bind
with their specific antibody at an optimum temperature and pH, resulting in the
formation of an insoluble precipitate.
·
The interaction between the soluble antigen and antibody results
in the formation of insoluble lattice that forms precipitate out of the
solution.
·
The process of precipitation has some requirements involving the
valency of both the antigen and the antibody.
·
For precipitation to take place, the antibody must be bivalent,
and the antigen must be either bivalent or polyvalent.
·
Precipitation takes place in the zone of equivalence, where the
concentration of antigen and antibody is equal. On either side of equivalence,
precipitation doesn’t occur if the concentration of either antigen or antibody
is in excess or deficient.
·
Immunological techniques like immunodiffusion and
electroimmunodiffusion utilize the principle of precipitation reactions.
·
The principle of precipitation is also applied in analytical
chemistry for the detection of various functional groups of chemical
substances.
·
If a lighter precipitate is formed, another process, termed
flocculation, takes place. In flocculation, the precipitate floats instead of
sedimenting.
·
Precipitation reactions are commonly performed on semi-solid
surfaces like agar media or non-gel support media like cellulose acetate.
·
The precipitate formed in the reaction remains suspended until
enough force of gravity can settle the precipitate towards the bottom of the
surface.
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