This presentation discusses about an immunotechnique - radial immunodiffusion.

1. RADIAL IMMUNODIFFUSION
BY: M. JANANI
III B.SC. ZOOLOGY

2. INTRODUCTION
• Antigens are mainly proteins and polysaccharides. They stimulate the
production of antibodies in an organism.
• Antibody is a glycoprotein that is formed in response to an antigen.
• Diagnostic methods that determine and measure the concentration
of antigens and antibodies are known as immunotechniques.
• They have many applications in the field of medicine, agriculture and
industries.
• There are 18 different immunotechniques. One of it is Radial
immunodiffusion.

3. DEFINITION
• It is also known as single radial diffusion.
• It is the immunological technique in which antigen alone diffuses
through the gel in all directions from the well.
• It helps in determining the concentration of antigens in a sample.
ANTIGEN CONTAINING
SAMPLE
ANTI SERUM + AGAR PRECIPITIN BAND

4. PROCEDURE
• Different antigens are isolated by using biochemical methods.
• It is ground well and injected into the blood stream of a rabbit.
• After 4-5 hours blood is taken from the rabbit using a syringe.
• The blood is centrifuged and the anti-serum is used as antibody
sample.
• 1g Agar + 100ml Borate Buffer ; heated
• Antiserum is added.
• This mixture is poured on a glass slide using a pipette. It is allowed to
settle for 30 minutes.

5. • A circular well is made in the agar slab using a cork borer.
• The antigens are loaded into the well using micropipette.
• Incubated for 1 day.
• Washed with borate saline and stained with amidoblack dye. Washed
with water and examined under microscope.
OBSERVATION:
The antigen in the well diffuses through the gel and forms antigen-
antibody complexes around the well. So, a circular precipitin band is
formed around the well.
The diameter of the band depends on the concentration of antigen.

6. USES
• Determine the quantity of different antigens
• Estimate the concentration of various immunoglobulin.
• For disease diagnosis
• More sensitive and specific results are obtained.