Week 2 (reaction test methods)

what is specificity?

only binds to the one thing we’re looking for, ability to identify negative results

what is cross reactivity?

binds to things other than the 1 thing we’re looking for

what is sensitivity?

ability to detect a positive result

what is analytical sensitivity?

lowest amount detected

what is clinical sensitivity?

probability of getting a positive if the patient is in fact positive

what is Affinity

sum of attractive and repulsive forces, strength of the interaction

what is avidity?

strength of the binding between a multivalent antibody and a multivalent antigen

what does multivalent mean?

multiple contact points/ can bind to multiple things

what is the zone of equivalence?

when the amount of antigen present is equal to the amount of antibody present

what is a hybridoma?

myeloma cells crossed with antigen B cells to create antibodies for clinical use

what does monoclonal mean?

all from one type of B cell makes 1 type of antibody for one target

what does polyclonal mean?

from different lineages of B cells makes 1 type of antibodies with multiple binding points on the same target

what is direct agglutination? what is an example?

antibody binds onto antigen one to one

what is co-agglutination?

multiple antibodies and antigens all bind together as one big group

what is passive agglutination?

antibody binds to antigen presented on a carrier molecule

what is reverse passive agglutination?

antigen is presented with antibody on a carrier molecule

what are the two types of precipitation reactions that we measure?

turbidity and nephelometry

at what angle is light measured for turbidity?

180

at what angle is light measured for nephelometry?

90

what test method is the main way we measure antibodies?

nephelometry

how does an immunoassay work?

uses antibodies that bind to other specific antibodies to isolate bands within electrophoresis of a sample

what is a fluorochrome?

florescent antibody tags

when are immunoassays most useful?

to detect analytes at very low concentrations

what is a detector molecule in an immunoassay?

antibody label

immunoassays are representative of analyte concentrations because…

signal from detector is only visible after binding has occurred if it occurs at all

besides the detector molecule and antibodies what else do we need for analyte detection?

standards and calibrators

how does a lateral flow rapid test work?

fluid draw from capillary action wicking sample to test and control line, the test line is specific to antigen, testing antibody is specific for the control line

Do heterogenous immunoassays require a wash step? why/why not?

yes, otherwise unbound antibody would also contribute to detection

Do Homogeneous immunoassays require a wash step? Why or why not?

no, the detection mechanism only works if the antibody binds to the target

what is a noncompetitive assay?

measures the amount of antibody bound detection directly proportional to the amount present in the patient

what is a competitive immunoassay?

patient sample and competitor are both in solution, the signal detected is inversely proportional to the amount in the patient

what is the post zone hook effect?

when there is way more antigen than antibody present