The document discusses immunofluorescence, a technique that uses fluorescent-labeled antibodies to detect specific antigens in tissues, viewed under a fluorescence microscope. It outlines the principles of direct and indirect immunofluorescence methods and their applications in clinical diagnoses, notably for skin diseases. Limitations include factors like antibody quality and specimen handling that can affect fluorescence signals.

1. Immunofluorescence
Tapeshwar Yadav
(Lecturer)
BMLT, DNHE,
M.Sc. Medical Biochemistry

2. Introduction:
 Immunofluorescence : Immunofluorescence is a
powerful technique that utilizes fluorescent-labeled
antibodies to detect specific target antigens..
 Fluorescein is a dye which emits greenish fluorescence
under UV light. It can be tagged to immunoglobulin
molecules.
 This technique is sometimes used to make viral plaques
more readily visible to the human eye.
 Immunofluorescent labeled tissue sections are studied
using a fluorescence microscope.

3. Immunofluorescence assay
 Immunofluorescence is a technique allowing the
visualization of a specific protein or antigen in
tissue sections by binding a specific antibody
chemically conjugated with a fluorescent dye
such as fluorescein isothiocyanate (FITC).
 The specific antibodies are labeled with a
compound (FITC) that makes them glow an
apple-green color when observed
microscopically under ultraviolet light.

4. • Fluorescence is the property of certain
molecules or fluorophores to absorb light at
one wave length and emit light at longer wave
length (emission wavelength) when it is
illuminated by light of a different wavelength
(excitation wavelength).
• The incident light excites the molecule to a
higher level of vibrational energy. As the
molecules return to the ground state, the
excited fluorophore emits a photon(=
fluorescence emission ).

5. Examples Of Fluorescent Dyes
Fluorescein Rhodamine

6. Principle of the Test

8. FLUORESCENCE MICROSCOPY

9.  There are two ways of doing IF staining
 Direct immunofluorescence
 Indirect immunofluorescence
1. Direct immunofluorescence
 It’s just a simple & a very common procedure in this
regard.
 Ag is fixed on the slide
 Fluorescein labeled Ab’s are layered over it
 Slide is washed to remove unattached Ab’s
 Examined under UV light in an fluorescent microscope
 The site where the Ab attaches to its specific Ag will
show apple green fluorescence
 Use: Direct detection of Pathogens or their Ag’s in tissues
or in pathological samples.

10. Direct immunofluorescence

11. 2. Indirect immunofluorescence:
 Indirect test is a double-layer technique
 The unlabelled antibody is applied
directly to the tissue substrate
 Treated with a fluorochrome-conjugated
anti-immunoglobulin serum.

12.  Advantage over direct IF
Since several fluorescent anti-immunoglobulins
can bind to each antibody present in the first
layer, the fluorescence is brighter than the
direct test.
It is also more time-efficient since it is only one
signal labelled reagent, the anti-
immunoglobulin, is prepared during the lengthy
conjugation process.

16. Confocal image to detect phosphorylated AKT (green)
in cardiomyocytes infected with adenovirus

17. Immunofluorescence image of Cryptosporidium parvum oocysts

20.
Concentrated groundwater methanotrophic bacteria on 0.2 µ m
filter labeled with fluorescent antibodies.

21. What Immunoflouroscence Does
 Immunoflourescence is a Microscopic-based technique,
used clinically to diagnose certain cutaneous diseases
( e.g; Lyme Disease) by the detection of AG:AB
Complexes.
 Techniques including DIF, IDIF & Salt-split
Skin are utilized depending on clinical scenario.
 DIF is performed on patient’s skin using flourophore-
labeled antibodies that directly bind to pathogenic
autoantibody-antigen complexes in the skin.

22. What Immunoflouroscence Does:
 IDIF techniques are used in Dermatology primarily to
detect circulating pathogenic autoantibodies.
LIMITATIONS
 Fluorescence signals depend on the quality &
Concentration of antibodies, proper handling of
specimen & detection with appropriate secondary
antibodies.

23. THANK YOU