VLD 421: Veterinary Clinical Biochemistry and Laboratory Diagnosis-II (0+1)

PRINCIPLE - TUBE AGGLUTINATION TEST

• Agglutination refers to aggregation into clumps of  particlulate antigens like bacteria, uniformaly distributed in the required solution by specific union with antibodies.
• The antigen and antibodies in agglutination reaction are called as agglutinogen and agglutinin respectively.
• In agglutination  test a constant volume of a cell suspension (antigen) is added to same volume of two fold dilution of antiserum.
• The mixture is incubated at 37 c , after which the visible clumping or agglutination occurs due to cross linking of antibody with particulate antigen which is observed by direct inspection.
• Agglutination is due to neutralization of negative charge antigen " Zeta potential " with the positive charge of antibody.

Zone Phenomenon

• Zone of equivalence              
• Antibodies and antigens present in optimum ratio, agglutination formed
• Pre Zone or Pro zone phenomenon
• A zone in which the agglutination is not observed in undiluted serum or serum with less Zone of equalence.
• Post Zone phenomenon
• In higher dilutions of serum, a zone in which no agglutination occurs due to in sufficient amount of antibody to agglutinate antigens.