Exam 2 Flashcards
(38 cards)
precipitation
unlabeled assay that involves a soluble antigen with a soluble antibody that produces an insoluble visible complex
agglutination
unlabeled assay that involves specific antigens that aggregate together to form larger visible complexes when a specific antibody is present.
prezone
too much antibody
post zone
too little antibody
ouchterlony immunodiffusion
-tests if antibody response develops
- identical = bell curve
- non-identical = two straight lines intersecting at top
- partially identical = one straight line and one curved line
radial immunodiffusion
antibody is distributed throughout gel and different antigens are put in separate wells..measure for zone of equivalence
two steps in agglutination are?
- sensitization- initial ab-ag binding (not visible)
2. lattice formation/cross-linking- intermolecular ag-ab binding (visible)
most effect Ig for agglutination?
IgM
direct agglutination
antigen is naturally part of particle. tests for unknown antibody.
Example: ABO blood group typing
passive agglutination
aka indirect.
antigen is not normally part of particle so it is bound to an inert particle like latex beads to detect pt antibody.
example: syphillis RPR
reverse passive agglutination
antibody is attached to carrier particle. tests for pt antigen
example: strep test
agglutination inhibition
based on competition between antibody and antigen. tests for antigen.
no agglutination = positive reaction
example: illicit drug tests
electrophoresis
separates serum proteins by their shape, size, and electrical charge
IFE
???? look up
direct
reagent is directly attached to the label.
antibody reagent has specificity for certain antigen
indirect
reagent is indirectly bonded to label (anti-human Ig is usually middle component)
more sensitive but takes longer
doesn’t have specificity for antigen
Sandwich/Capture
ELISA
capture antibody will bind with pt’s antigen. then an enzyme-tagged detection antibody will create a read out via color change.
common enzymes
horseradish peroxidase (HRP) alkalkine phosphatase (AP)
common substrates
TMP for HRP
p-nitrophenol for AP
colloidal/rapid assay
indirect labeled assay where the reactant is an antibody labeled with gold particles.
test strip 1st, control strip 2nd.
example: pregnancy tests
fluorescence polarization
antigen is fluorescently labeled and placed in urine with potential antigen..if antigen is not present, the polarization of light will be consistent due to identical binding. if antigen is present, the polarization of light will vary dues to both labeled antigen and non-labeled antigen binding (drug screens)
fluorescence emission
molecule absorbs light then becomes activated.
after it reaches it’s grow state it will emit the energy in the form of light at different wavelengths.
Heterogenous assays
- multiple steps with washing to remove unbound ag/ab
- more sensitive
- ELISAs/indirect assays
Homogeneous assays
one step with no washing
- not as sensitive but faster
- fluorescence/polarization/agglutination/precipitation