On the short description of a large and broad topic named as IMMUNOHISTOCHEMISTRY

1. Immuno-Histo-Chemistry
(IHC)

2. LEARNING OUTCOMES
What is IHC
What is ABC Method
What’s it significance
What’s its principle
Advantages and Disadvantages

3. What is Immunohistochemistry
It is a technique in which antibodies used to test to detect for
certain antigens in tissue. The antibodies are usually labeled
with enzymes or fluorescent.
Immuno means immunological reaction
Histo means dealing with tissue
Chemistry means use of proteins color genic molecules
containing antibodies to detect antigens.

4. What is Avidin-Biotin Complex
The ABC method
incorporates a large
glycoprotein called
avidin(AV) that has a very
high affinity for a low
molecular weight vitamin
called Biotin.
Avidin can be labeled with
peroxidase or fluorescein .
Biotin can be conjugated to
antibodies.

6. METHOD:
The technique methodology consists of using:
1. Unlabeled primary antibody
2. Biotinylated secondary antibody
3. Complex of avidin-biotin peroxidase
4. The peroxidase is then developed by the DAB or
other substrates to produce a colored label.

7. Significance of ABC method:
Avidin–biotin binding is the strongest known non-
covalent interaction between a protein and ligand. The
bond between biotin and avidin is formed very rapidly,
and once formed, is unaffected by extremes in pH,
temperature, organic solvents and other denaturing
agents.
 These features of avidin make detecting or purifying
biotin-labeled proteins or other molecules particularly
useful for a number of biomedical applications.

8. Principle:
The basic principle of this method is that avidin (or
streptavidin) reacts with a biotinylated secondary
antibody, followed by a peroxidase reaction.

9. Avidin-biotin complex
Advantage:
Increase enzyme
reporter localized to the
target antigens.
It Increase detection
efficiency.
Requires less primary
antibody then direct
method of antibody
detection.
Disadvantage:
Some tissue may
requires endogenous
biotin blocking to avoid
non specific labelling.
The Avidin-biotin-
complex is large, which
hinders tissue
penetration in some
applications.