Antigen-antibody Flashcards
reacts only with antibodies produced by itself
antigen
recognize molecular shapes on antigen
antibodies
the better the fit of the epitope, the ___
the higher the affinity of the antibody for antigen
an interaction similar to lock and key
antigen-antibody reaction
molecule formed from the binding of multiple antigens to antibodies
immune complex
act as unitary object, effectively an antigen of itw own with a specific epitope
bound antigen and antibody
part of the antigen which combines with the antibody
epitope
epitope also known as?
antigenic determinant
epitope is the part of the antigen that is recognized by the immune system, specifically by:
- antibodies
- B cells
- T cells
part of the antibody that recognizes the epitope
paratope
3 factors in the binding force of antigen-antibody reaction
- closeness between ag-ab antibody
- non-covalent bonds or intermolecular forces
- affinity of antibody
The bonds that hold the antigen to the antibody combining site are all non- covalent in nature
non-covalent bonds or intermolecular forces
non-covalent bonds or intermolecular forces include?
- hydrogen bonds
- electrostatic bonds
- Van der Waals forces
- hydrophobic bonds
properties of ag-ab reaction
- affinity
- avidity
- cross reaction
affinity and avidity are both measures of?
binding strength
Measure of the binding strength at a single binding site
affinity
Measure of the total strength
avidity
applications of ag-ab reaction (5)
- Determination of blood groups for transfusion
- Serological exposure to infectious agents
-
Development of immunoassays for the
quantification of various substances - To detect the presence or absence of protein in serum
- Determining the characteristics of certain
immunodeficiency disease
types of ag-ab reactions
8
- Agglutination
- Precipitation
- Complement Fixation
- ELISA
- Immunofluorescence
- Radioimmunoassay
- Immunofixation
- Immunoelectrophoresis
a particular Ag is mixed with its Ab’s in the presence electrolytes at a suitable temperature and pH
agglutination
The Ab of the serum causes the cellular Ag’s to form clumps, and these are called ___
Agglutinins
participate antigens that are aggregated
agglutinogens
rapid method to determine the presence of agglutinating antibodies
slide agglutination
agglutination is the test used for?
blood grouping and cross matching
sol’n needed for agglutination
antiserum and nss
a standard method for quantitative estimation of Ab
tube agglutination
a tube with no antiserum is the
control tube
the tube that shows highest agglutination is referred to as?
titer
tube agglutination is used for the serological diagnosis of?
- typhoid fever
- brucellosis
- typhus fever
test for determining
antibody titer
tube agglutination
antigen binds with Fab sites of two antibodies forming bridges between
antigens
lattice formation (clumping)
what agglutination principle in which an antigen reagent produced by treating RBCs with tannic acid to allow adsorption of protein antigens
passive hemagglutination
what agglutination principle in which the antigen in reagent is attached to latex
particle
Passive Latex agglutination
test for agglutination inhibition
posi:
nega:
posi = no agglutination
nega = agglutination
AGGLUTINATION INHIBITION
If patient has antigen for which you are testing, the reagent antibody will be bound in step 1 and unavailable to react with the
indicator, what could be the result?
positive
If patient does not have the antigen, reagent antibody is not bound in step 1 andis available to react with indicator, what could be the result?
AGGLUTINATION INHIBITION
negative
Hemagglutination inhibition is the test for?
rubella
examples of inhibition reactions (tests)
- hemagglutination inhibition test
- latex agglutination inhibition test
When a soluble Ag combines with its Ab in the presence of an electrolyte (NaCI) at a particular temperature and pH
precipitation
ab causing precipitation
precipitin
enumerate the examples of precipitation principle
DSII
- double diffusion: ouchterlony
- single diffusion: radial immunodiffusion
- immunoelectrophoresis
- immunofixation
Lysis of rbc or bacteria requires non-specific
unstable components of fresh serum
complement fixation
unstable components of fresh serum
complement
complement fixation test
posi =
nega =
P = no hemolysis
N = hemolysis
If complement is fixed in step 1, it will not be available to combine with indicator, what could be the result?
positive
Complement was not bound in step 1 and is available to react with indicator, what could be the result?
negative
complement fixation is used only for what antibodies?
IgM
limitations of complement fixation
- Serum MUST be heat inactivated
- Stored serum becomes anticomplementary
- Elaborate QC and standardization required
- Only used for IgM ANTIBODIES
enzyme linked immunoassay (EIA/ELISA) was known to be the?
sandwich technique
sample needed for ELISA
serum
ELISA
improper washing could lead to?
false positive
ELISA
absorbance is ____ proportional to antigen concentration
directly proportional
examples of ELISA
- HIV testing
- serum HCG (pregnancy)
- test for hepatitis antigens and antibodies
- antibodies to bacteria and viruses
the property of absorbing light rays of one particular wavelength and emitting rays with a different wave length.
immunofluorescence
fluorescent dyes show up brightly under?
UV light
▪ add fluorescein-labelled antibody to patient tissue
▪ wash & examine under florescent microscope
what type of immunofluorescence?
direct
▪ Add patient serum to reagent (tissue containing
known antigen)
▪ wash, add fluorescein labelled antiglobulin
▪ wash & examine under fluorescent microscope
what type of immunofluorescence?
indirect
examples of HF
- testing for antinuclear antibodies (ANA)
- fluorescent treponemal antibody test (FTA-Abs)
VERY SENSITIVE and SPECIFIC, Can be used for detecting antigen or antibody
radioimmunoassay
The ___the radioactive count, the __ the concentration of unlabeled antigen (patient)
The LOWER the radioactive count, the HIGHER the concentration of unlabeled antigen (patient)
a series of points that are arranged in a distinct pattern
lattice
this uses antibodies to detect and quantitate the amount of antigen (analyte) in a sample.
radioimmunoassay (RIA)
enumerate the nonlattice (more sensitive) tests
- immunoassays
- nephelometry
enumerate the lattice (less sensitive) tests
always remember the CRROII
- counter current immunoelectrophoresis (complement fixation, agglutination, flocculation)
- rocket electrophoresis
- radial immunodiffusion
- ouchterlony (double immunodiffusion)
- immunofixation
- immunoelectrophoresis
enumerate the immunoassays
REF
- radial immunoassay
- enzyme immunoassay
- fluorescent immunoassay
higher vs. lower sensitivity (mg/ml)
H = 0.001 mg/ml
L = 500 mg/ml
