CHAPTER 6 - AGGLUTINATION Flashcards
Process by which particulate antigens (agglutinogen) such as cell aggregate to form larger complexes when a specific antibody (agglutinin) is present
AGGLUTINATION
particulate antigens
agglutinogen
specific antibody
agglutinin
published the first report about the ability of antibody to clump cells, based on observations of agglutination of bacterial cells by serum
Gruber and Durham
2 STAGES OF AGGLUTINATION
Antigen-Antibody reaction
SENSITIZATION
Cross linking
LATTICE FORMATION
Visible agglutination
LATTICE FORMATION
No agglutination yet
SENSITIZATION
Forms bridges between Ab and Ag
LATTICE FORMATION
Represents binding of Ag and Ab
SENSITIZATION
Stabilization of antigen–antibody complexes with the binding together of multiple antigenic determinants.
SENSITIZATION
FACTORS THAT AFFECT AGGLUTINATION
Routine Buffer pH
pH 7
(physiological pH)
7.35 – 7.45
Affects the zoning phenomenon
Relative concentration of Ag and Ab
Abs will not detect determinants buried within the particle
Location and concentration of Antigenic determinants of the particle
More number of determinants, the higher the likelihood of cross bridging
Location and concentration of Antigenic determinants of the particle
Electrostatic interactions between particles
Non covalent interaction
(Zeta potential)
Electrolyte concentration
in the buffer plays an important role in agglutination
Electrolyte concentration (ionic strength)
: charge bet RBC and the elctrolyte/ECF
Zeta potential
Zeta potential:
in RBC
outside the body
↑
↓
reduce electrostatic charges that interfere with lattice formation
Electrolytes
Antibody isotope Best: l
IgM
(dealing w/ particulate Ag)
IgM
IgM: Cold reacting with optimum temperature at
4-22oC
IgG: Warm reacting with optimum temperature at
37oC
Incubation times ranges from
15-60 minutes
No agglutinates
0
Dark, turbid, homogenous
0
Many tiny agglutinates, many free cells, may not be visible without microscope
W+
Dark, turbid
W+
Many small agglutinates, many free cells
1+
(25% are agglutinated)
1+
Turbid
1+
Many medium sized agglutinins, moderate number of free cells
2+
(50% are agglutinated)
2+
Clear
2+
3+
4+
Several large agglutinates, few free cells
3+
(75% are agglutinated)
3+
One large solid agglutination, no free
4+
(100% are agglutinated)
4+
MAJOR CATEGORIES OF AGGLUTINATION REACTIONS
Reaction is due to an Ag-Ab reaction where in the Ag is inherent (inside) native to the cell
Direct Immune