PRELIM LABORATORY L2: HEMAGGLUTINATION REACTION Flashcards
direct hemagglutination is aka
specific hemagglutination
importance of direct hemagglutination
most important in vitro immunologic reaction
why is direct hemagglutination most important in vitro immunologic reaction
because it is the endpoint of almost all test systems designed to detect RBC antigens and antibodies
two stages of gemagglutination
RBC sensitization
Latticework formation
what is rbc sensitization
combination of paratope and epitope in a reversible reaction that follows the law of mass action and has an equilibrium constant
what attractions hold antigen and antibody together
non-covalent attractions
what happens in stage two of hemagglutination
multiple rbcs with bound antibody form a stable latticework through antigen-antibody bridges
what is the basis of all visible agglutination reactions
latticework
T or F:
hemagglutination reaction only ends with latticework
F
it can also lead to cell lysis
what factor leads to cell lysis
activation of complement system
strongest hemagglutination reaction
cell lysis
positive charges that keep the rbc repel each other
zeta potential
description: 4+
single clump of agglutination with no free cells
description: 3+
three or four individual clumps with few free cells
description: 2+
many fairly large clumps with many free cells
description: 1+
fine granular appearance visually, but definite small clumps (10-15 cells ) per LPF
description: +W
2-3 cells sticking together per LPF, uneven distribution; visually no agglutination
description: H
hemolysis (partial/total) must be interpreted as positive
description: -
all cells are free
factors affecting hemagglutination
ionic strength of the medium
temperature of the reaction
degree of contact of antibody coated cells
electrical charge of red cells
span of antibody molecule
location and density of antigen site
capacity of antibody to bind complement
methods of agglutination
tube method
gel card method
solid phase red cell adherence (SRCA)
pros of tube method
easy to perform
requires minimum equipment
flexible to tube
cons of tube method
labor intensive
time consuming
unstable result; requires skilled reading
prone to error due to human intervention
who described the technique used in gel method
Yves Lapierre, 1984
the chamber of the microtube is aka
incubator
long and narrow microtube is called
column
what does the gel column do
acts as a filter that traps agglutinated rbcs as they pass through the column
pros of gel card method
standardized
faster
more sensitive
less prone to operator error
needs smaller samples
can be performed in batches
cons of gel card method
more expensive
less flexible
SPRCA stands for
solid phase red cell adherence
principle of SPRCA
red cell adherence
what is SRCA
method of testing for incompatibility between plasma antibodies and target rbc antigens
pros of SRCA
highly specific and sensitive
less amendable to innovation
