Exam 3 Chapter 10 Flashcards
What is epitope
antigenic determinant: part of the antigen that binds to the antibody’s Fab triggering the production of antibody or activating T cells
What is hapten
an antigen too small to illicit production of antibody by itself, must be bound to a larger carrier
What is affinity
the initial force of attraction between a single antigen-binding site on an antibody molecule and a single epitope of the corresponding antigen
What is avidity
the overall strength of antigen-antibody binding produced from the sum of the binding sites
Define precipitation immunoassays
a soluble antigen combined with soluble humongous antibody to produce insoluble complexes that are visible as lattice formations
Define agglutination immunoassays
these form a visible aggregation (cluster) of particles resulting from combination with specific antibody; visible clumps it is mostly qualitative (measured by the quality of something rather than its quantity) indicating the absence or presence of ag or ab
Soluble + soluble=
insoluble (this is visible as lattice formation)
What is the prozone
the zone of antibody excess, the antigen combines with only one or two antibody molecules
What is the zone of equivalence
the number of multi-valent sites of antigen and antibody are approximately equal, precipitation reactions must be run in this zone
What is the postzone
the zone of antigen excess, small aggregates are surrounded by excess antigen, the presence of a small amount of antibody may be obscured causing a false-negative reactions
Where does optimal lattice formation become visible
in the zone of equivalence
Where does the visible lattice formation become soluble again
in the postzone
Describe the types of automated precipitation methods
Immunoturbidimetry -measures reduction in light intensity due to turbidity or cloudiness
Nephelometry - measures light that is scattered at a particular angle from the incident beam as it passes through suspensions
Describe types of manual precipitation methods (RID) Radial immunodiffusion
a manual single diffusion technique, antibody is in the support gel and antigen is placed in a well cut into the gel, antigen diffuses out and reacts with antibody to form a ring of precipitation around the well
Describe types of manual precipitation methods (Ouchterlony)
a manual double diffusion technique, wells are cut into a gel, and both antigen and antibody diffuse out radially, a line of precipitate forms when antigen and antibody meet in equivalent amounts
What are the three possible patterns of Ouchterlony
Identity- fusion of the lines are their junction to form an arc represents serological identity
Non-identity- a pattern of crossed lines demonstrates two separate reactions and indicated that the compared antigens have no common epitopes
Partial identity- indicated by a fusion of two lines. Two antigens share a common epitope. The spur points to the AG that reacts lest to the Ab
Describe types of manual precipitation methods (Immunofixation electrophoresis (IFE))
a double diffusion technique, performed to visualize increased or decreased production of antibody classes and to differentiate monoclonal and polyclonal immunoglobulins
What are the types of agglutination reactions
direct agglutination, passive agglutination (indirect), reverse passive agglutination, and agglutination inhibition
Describe direct agglutination
uses particles with naturally occurring antigens to test for antibodies in patient serum (antigens are found naturally on the indicator particle), this is the best method to test for patient antigen in tissues
What is hemagglutination (direct agglutination type) and when can it happen
an agglutination of RBCS, can happen during ABO typing (blood banking) when a and b antigens are on the red blood cells are mixed with anti-A, anti-B, and anti-D antibodies to determine blood type
Describe indirect agglutination (passive)
uses particle that are coated with antigens not normally found on their surfaces (Erythrocytes, latex, gelatin, and silicates), the antigen is artificially attached to the carrier particle such as synthetic beads; incubated with patient serum
detects the presence of antibody
Describe reverse (passive) agglutination
antigen is attached to the carrier (indicator) particle and agglutination occurs if antibody is present in the patient sample
Describe agglutination inhibition
based on competition between particulate and soluble antigens for limited antibody-combining sites
lack of agglutination= positive reaction
agglutination represents a negative
used to detect hapten antigens such as cocaine or heroin
What is hemagglutination inhibition
uses RBCs
used to detect antibodies to certain viruses that can bind to RBCs and agglutinate them
-rubella
-influenza
-respiratory syncytial virus (RSV)
