Immunoassay methods Flashcards
What is an Immuno assay method test?
A test that uses antibody and antigen complexes as a mean to generate a measurable result
What is an antigen complex also known as?
also known as an immuno complex
What is an analyte?
anything measured by a lab test. In immunoassay testing, the analyte may be either an antibody, or an antigen
Immunoassays utilise one or more antibodies to detect analytes of intrest
The analytes consist of:
- Naturally present in the body (such as thyroid hormone)
- Those that the body produces but are not typically present
- those that do not naturally occur in the body ( such as an abused drug)
2 cartorgories of Immunoassay Methodologies
- Non competitive and competitive immunoassays
2. Homogenous and Heterogenous immunoassays
What do immunoassays require?
the use of labelled material
describe competition format?
Unlabelled analyte in the test sample is measured by its ability to compete with a labelled antigen in the immunoassay
blocks the ability of the labelled antigen to bind
what’s one step competitive format?
Both the labelled antigen reagant (Ag) and the unlabelled specimen compete for a limited amount of antibody
What’s two step cometitive format?
The antibody conc. of the reaction solution is present in excess in comparison to the conc. of antigen
Non competitive method
provide highest level of sensitivity and specifity
known as a sandwich–> due to analyte bound between 2 highly specific antibody reagants
Describe Homogenous methods?
do not require separation of bound Ab-Ag complex
Describe Heterogenous methods?
require separation of bound Ab-Ag complex
Whats sensitivity?
Proportion of true positives correctly identified by test
Whats Specificty?
Proportion of true negatives correctly identified by test
Describe Immunocytochemical staining?
Reveals subcellular or tissue distribution of specific antigens
