Immunology Lecture: Primary Reactions Part 2 - Immunofluorescence and Chemiluminescence

Practice vocabulary flashcards covering the principles, history, and techniques of immunofluorescence and chemiluminescence as discussed in the lecture notes.

Secondary Reaction

A reaction where only the results, such as Agglutination, Precipitation, or CFT, are visible rather than the direct union of antigen and antibody.

Primary Reaction

A reaction in which the union of antigen and antibody is visible due to labels such as radioisotopes or enzymes.

Tagging

The process of attaching a label to an antibody or antigen for detection.

Horseradish peroxidase

The most common enzyme label used in Enzyme Immunoassay (EIA).

Immunofluorescence Technique

A histochemical or cytochemical technique introduced by Albert Coons in $1941$ for the detection and localization of antigens using fluorescent dyes.

Fluorescence

The emission of light of one color or wavelength while a substance is irradiated with light of a different color.

FITC (Fluorescein isothiocyanate)

A fluorescent dye that absorbs UV or short blue light at $490-495\,nm$ and emits a characteristic green color at $517\,nm$.

Fluorochrome

Also known as a fluorophore, it is a chemical compound that absorbs electromagnetic energy of a short wavelength and instantaneously emits light at a longer frequency or lower energy level.

Tetramethylrhodamine isothiocyanate

A popular fluorochrome that emits a red color upon excitation.

Fc region

The part of the immunoglobulin protein where epsilon amino residues of lysine bind to fluorochromes during tagging.

Mercury vapor arc lamp

The component of a fluorescent microscope that produces an intense beam of light used to excite the dye.

Exciter Filter

A part of the fluorescent microscope that transmits only the desired wavelength needed to excite the fluorochrome.

Barrier Filter (Lens)

A lens that removes remaining ultraviolet light to protect the viewer's eyes and filters out blue or violet light that could reduce image quality.

Quenching

A factor affecting measuring results where there is a decrease in fluorescent intensity due to fluorochrome interaction with other molecules in the solvent.

Direct Immunofluorescence Test

A single layer technique used to identify an unknown antigen by adding a fluorescein-labeled antibody directly to the tissue or cell suspension.

Indirect Immunofluorescence Test

A double layer technique, often an adaptation of the Coomb's Test, used to detect antibodies in unknown or unlabeled sera by using a labeled antiglobulin.

Inhibition Technique

A procedure where an unlabeled antibody saturates antigen sites first; a positive result is indicated by the absence or reduction of fluorescence when labeled antibody is subsequently added.

Avidin

A basic glycoprotein derived from egg albumin with a molecular weight of $68,000$ that has a remarkably high affinity ($1015\,K\,cal/mol$) for Biotin.

Microfluorometer

An instrument used for quantitative fluorescent antibody techniques that measures fluorescence spectra of microscopic samples and can measure $IgG$, $IgA$, $IgM$, $C3$, and $C4$.

Luminescence

The emission of light from a substance as it returns from an electronically excited state to the ground state.

Chemiluminescence

Light produced by a chemical reaction, such as the reaction of $NO$ with ozone which yields nitrogen dioxide in an excited state.

Luminol

An organic compound with the formula $C_8H_7N_3O_2$ that emits blue light when oxidized; it is commonly used by forensic scientists to detect blood.

Photomultiplier tube

A component in a luminometer or fluorescence detection system that amplifies weak signals and converts light into electrical current.

Attamoles to Zeptamoles

The sensitive detection range of chemiluminescence assays, specifically from $10^{-18}\,mol$ to $10^{-21}\,mol$.