Network theory and it`s experimental
evidence
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Any
discussion regarding of immune response not come to the end without mentioning
Jern`s idiotype network theory.
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In
1973, Neil Jerne proposed this theory so to give possible solution for
regulation of immune system in 1985 he was honored with Nobel prize for this
work.
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This
theory suggest that antigen enter the inside the body and activate very
specific done of B cell secreting antibody against it.
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The
antigen binding site of an antibody composed of overlap between light and heavy
chain domain called as idiotype.
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This
recognizing are said to be complementary to antigen.
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Antibody
molecule itself being a protein so can behave as an antigen.
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Antibody
molecule against idiotype which exhibit internal image of an external antigen.
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Likewise,
anti-ant idiotype antibody as external images of primary antibody.
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Theoretically
this sequence can go further consisting network od idiotype antibodies, however
experientially it has been observed that is extend to just their steps.
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As
a consequence of such antibody network antigen is readily remove from
circulation.
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At the same time each antibody feedback regulates
formation of antibody once step ahead. Thus, controlling the overproduction of
antibody
Experimental
evidence: -
Hemolytic plaque assay (jern`s
hemolytic assay)
1.
This
assay is used to quality number of antibodies producing plasma cell.
2.
Assay
was introduced by jern`s and modified by qunning in 1968.
Protocol: -
Ø
First
mouse is immobilized with sheep RBCs
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After
a fixed incubation period the spleen from mouse isolated.
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Then
the solenocytes from the spleen are separated which contain plasma cell and
this plasma cell produce antibody against sheep`s RBC`s.
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A
microchamber of slides is prepared using two slides.
Ø
The
solenocytes are introduced in the microchamber along with sheep RBC`s and
complement protein.
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The
microchamber is incubated at 370c for 2-3 hours.
Ø
During
this incubation period, plasma cell secretes the antibody against RBS`s (of IgM
type).
Ø
The
secreted antibodies then bind to sheep RBC`s present in surrounding.
Ø
Once
antibody binds to sheep RBC`s present in surrounding.
Ø
Once
antibody binds to sheep RBC`s complement lysis the RBC`s.
Ø
Due
to this lysis of RBC`s a clear zone is produced around the antibody producing
cell.
Ø
Number
of plaques are directly proportion to number of antibodies producing plasma
cell.
Ø
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