ANTIGEN ANTIBODY REACTION

1
ANTIGEN ANTIBODY REACTION
By
Dr. Emad AbdElhameed Morad
Lecturer of Medical Microbiology and Immunology
2
Precipitation

• It is a form of antigen antibody reactions in
  which the antigen is soluble.
• Types this reaction can be done in

Tube
Agar gel
3
Precipitation in tube

• When solutions of the antigen and antibody are
  mixed in tubes, cloudiness or turbidity occur.

4
Precipitation in agar

• Example Eleks test.
• A strip of filter paper saturated with diphtheria
  antitoxin is embedded in the agar plate.
• Diphtheria is inoculated at right angles to the
  filter paper, then plates are incubated for two
  days at 37 degree.
• If the organism is toxigenic, fine white lines of
  precipitation occur commencing from the streak.

5
(No Transcript)
6
Toxin antitoxin neutralization

• Example demonstrating toxigenicity of
  diphtheria.
• Injecting two guinea pigs with the diphtheria
  isolate.
• If the guinea pig protected with the antitoxin
  survives, while the unprotected one dies, the
  isolate is considered toxigenic.

7
Complement fixation test

• The serum of the patient (antibody) is added to a
  known antigen and then complement is added.
• If the serum contains antibodies to this
  antigen, they unite together and fix the
  complement.
• If the serum has no antibodies, the complement
  is left free in the solution.
• The second step is addition of sheep red blood
  cells coated with their antibodies.
• In negative sera, the complement is free so it
  will cause hemolysis of red cells.
• In positive sera, the complement is fixed and no
  hemolysis occurs.

8
(No Transcript)
9
(No Transcript)
10
(No Transcript)
11
GOOD LUCK