Serologic Tests

Antigenic site/determinant

Epitope

Ability to detect small amounts. Ability of a test to be POSITIVE

Sensitivity

Degree of uniqueness of Ab-Ag reaction. Ability of a test to be NEGATIVE

Specificity

Part of the antibody molecule that physically binds to the antigen

Paratope

Composed of 110-130 amino acids. Gives the ab its specificity for binding antigen

Variable region

Determines the mechanism used to destroy antigen

Constant region

Change of serologic test from negative to positive due to development of measurable antibodies

Seroconversion

Failure of a px serum to revert to non-reactive in non-treponemal test following treatment for syphilis

Seroresistance

Period between exposures to the antigen and development of detectable antibody

Window period

Antigen in excess, so insufficient reactive sites on an antibody for lattice formation

Postzone reaction

Antibody in excess, also insufficient reactive sites on an antigen for lattice formation; results to false negative results

Prozone reaction

Initial force of attraction that exist between single Fab site in the antibody and a single epitope in the corresponding antigen

Affinity

The strength of a single interaction

Affinity

Refers to the accumulated strength or sum total of multiple affinities of individual antigen-antibody interaction

Avidity

Incubation time in serologic tests

15-60 mins

Combination of Ag-Ab, non- visible reaction, visible only using LABELS

Primary reaction

With demonstrable Ag-Ab reaction. Visible reaction

Secondary reaction

Immunologically IN VIVO, biologic reaction detectable

Tertiary Reaction

FARR Technique/ NH4SO4 precipitation

Immunoassay

Primary reaction

Precipitation

Agglutination

Complement fixation

Neutralization

Secondary rxn

Phagocytosis

Opsonization

Chemotaxis

Tertiary reaction

Greatest dilution of the sample that yields positive result

Endpoint

Reciprocal of the endpoint

Titer

Measures transmitted light of a solution

Spectrophotometry

measures light energy scattered in a forward direction by small particles in a solution

Nephelometry

Measures unscattered light passing through a coloidal solution of a small particles

Turbidimetry

Measures light emitted by substances that have been previously excited by a source of UV light

Fluorometry

An _______ is an analytical method that uses antibodies or antigens as reagents to measure specific chemicals or analytes

Immunoassay