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1. Passive agglutination

2. Definition
 agglutination test done with a soluble antigen coated onto a
particle (Ag is fixed to a solid surface)
 Bind known ANTIGEN to inert particles to detect antibody
+ =

3.  Carrier molecules that can be used are :
 RBCs
 Polystyrene or latex particles
 Bentonite particle
 Human/sheep RBCs can absorb a variety of Ag
 Polysaccharide Ag (N.meningitides, mycoplasma )may be absorbed by simple mixing with the
cell
 Absorption of protein Ag ( Mycobacterium spps ) tanned RBCs are used

4. Procedure
Added to microtitre plate containing Ag coated RBCs
Serially diluted
Serum from the patient

5. Results and interpretation
 Agglutination reaction is assessed by
the spread pattern of the RBCs
 RBCs settles down
no agglutination
 Mat like appearance
agglutination
positive negative

6. Rose – Waaler test
 A special type of passive agglutination test
 In rheumatoid arthritis autoAb (RA factor ) serum
Ab to the gammaglobulin
 RA factor + RBCs coated with globulins agglutination
 Ag used is a suspension of sheep RBCs sensitised with rabbit anti –
sheep erythrocyte Ab
Acts as

7. Polystyrene latex
 Manufactured as uniform spherical particles
 Diameter – 0.8 to 1m
 Can absorb several types of Ag
 Detection of ASO, RA factor , HCG and many other antigens

8. Reverse passive agglutination
 Ab rather than Ag is attached to the carrier particle
 The Ab must still be reactive and is joined in such a
manner the active sites are facing outward.
 This type of testing is often used to detect microbial
Ags
 Latex particle coated with known Ab
+
serum
visible agglutination
( Ag present )
detecting cholera toxin

9.  Used for detection of microbial antigens:
 Group A and B Streptococcus
 Staphylococcus aureus
 Neisseria meningitidis
 Haemophilus influenzae
 Cryptococcus neoformans
 Mycoplasma pneumoniae
 Candida albicans