Untitled - D Ank Unlimited

precipitation in gel media 589 precipitation in gel media
Precipitation curves showing differences in the avidity of four antisera for the same antigen. The order of avidity of the sera is A > B > C > D.
E 0.5 cm (280 mµ)
Supernatants
excess Ab
excess Ag
Antibody Precipitated
precipitation in gel media
Oudin in 1946 overlaid antibody incorporated in agar in a
test tube with a homologous antigen. A band of precipitation
appeared in the gel where the antigen–antibody interaction
occurred. Mixtures of antibodies of several specificities were
+ + + + + + + +
+ + + + + + + + +
Antigen Added
Precipitin curve for multispecific system. The precipitation observed (⎯•⎯) is the sum of two or more precipitin reactions (---).
0.40
0.38
0.36
0.34
0.32
0.30
0.28
0.26
0.24
0.22
0.20
0.18
0.16
0.14
0.12
0.10
0.08
0.06
0.04
0.02
0
0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Weight of Thyroglobulin Added (mg)
Precipitation curve with human thyroglobulin and homologous antibody.
overlaid with a mixture of the homologous antigens, and a
distinct band for each resulted. Oudin’s technique involves
simple or single diffusion in one dimension. In 1953, Oakley
and Fulthorpe placed antiserum incorporated into agar in the
bottom of a tube, covered this with a layer of plain agar that
was permitted to solidify, and then added antigen. This process
was double diffusion in one dimension. Double diffusion in two
dimensions was developed by Ouchterlony and independently
by Elek in 1948. Agar is poured on a flat glass surface such as a
microscope slide, glass plate, or Petri dish. Wells or troughs are
cut in the agar, and these are filled with antigen and antibody
solutions under study. Multiple component systems may be analyzed
with this method and cross reactivities may be detected.
Double diffusion in agar is a useful method to demonstrate
similarity among structurally related antigens. Equidistant
holes are punched in agar gel containing electrolyte. Antigen is
placed in one well and antiserum in another adjacent to it, and
the plates are observed the following day for a precipitation line
where antigen and antibody have migrated toward one another
and reached equivalent concentrations. A single line implies a
single antigen–antibody system. If agar plates containing one
central well with others cut equidistant from it at the periphery
are employed, a reaction of identity may be demonstrated by
placing antibody in the central well and the homologous antigen
in adjacent peripheral wells. A confluent line of precipitate is
produced in the shape of an arc. This implies that the antigen
preparations in adjacent peripheral wells are identical, i.e., they
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