labeled immunoassay Flashcards
demonstrated that antibodies could be labeled with molecules that fluoresce
(1941) Albert Coons
Antibody that is conjugated with a fluorescent tag is added directly to unknown antigen that is fixed to a microscope slide
Direct Immunofluorescent Assays
patient serum is incubated with a known antigen attached to a solid phase. Slide is then washed and an anti-human immunoglobulin containing a fluorescent tag is added
Indirect immunofluorescent assays
homogeneous fluorescent immunoassay based on the change in polarization of fluorescent light emitted from a labeled molecule when it is bound by antibody
Fluorescence Polarization Immunoassay (FPIA)
emits an increased amount of polarized light
labeled molecule is bound to antibody
degree of polarized light reflects the amount of ______ that is bound
labeled analyte
degree of fluorescence polarization is inversely proportional to ________
concentration of the analyte
used to measure the amount of polarized light
Polarization analyzer
emission of light caused by a chemical reaction, (oxidation reaction) producing an excited molecule that decays back to its original ground state
Chemiluminescence:
Acridinium esters are oxidized by hydrogen peroxide which emit a quick ___ or _____ of light
burst or flash
longer flash of light
luminol
Detection system that is simple and relatively inexpensive
photomultiplier tubes
uses electrochemical compounds that generate light when an oxidation-reduction reaction occurs
electrochemiluminescence immunoassay
______ are often used as solid phase to capture the labeled antibody
Magnetic beads
traditional procedure detects the presence of a specific antigen-antibody reaction by causing the in vitro activation of complement.
complement fixation
If complement is not fixed, lysis of the ________ occurs
preantibody-coated reagent erythrocytes
1906 first nontreponemal serological test for syphilis was developed by _________
August Paul von Wassermann
This test used a crude liver extract from a fetus that was infected with syphilis as the source of the lipid antigen.
nontreponemal serological test for syphilis
the Wasserman test was based on the principle of ________.
complement fixation
patient serum was incubated with _______ in the presence of rabbit serum as the source of complement; this was followed by a detection system consisting of antibody-coated sheep red blood cells (RBCs). If the patient serum contained cardiolipin antibody, complexes were formed that bound the reagent complement and the indicator RBCs were not lysed.
cardiolipin antigen
In contrast, if cardiolipin antibody was ______ in the patient serum, the reagent complement was free to react with the antibody-sensitized sheep RBCs to cause hemolysis
not present
nontreponemal serological test for syphilis reaction results
+R: no hemolysis
-R: presence of hemolysis
similar to complement fixation, but can be used only when the antibody being measured is directed against a hemolysin (bacterial toxin capable of directly lysing red blood cells)
Neutralization
It is a diphtheria toxin-antitoxin neutralization test done to assess the immune status of a person. It was used in the past to know the susceptibility of individuals to Corynebacterium diphtheriae.
Schick test
Schick test is performed by ________ of 0.1 mL of a purified standardized toxin. If the patient has no antitoxin, the toxin will cause inflammation at the site _______ later. If _______ occurs, anti-toxin is present and the patient is immune.
intradermal injection ; 4 to 7 days ; no inflammation
