Virtual Immunology Lab Glossary

Aliquot - a portion of a solution

Antibody - a type of protein called an immunoglobulin found in the blood that is produced by immune cells in response to the presence of a foreign particle (antigen). Antibodies are specific to each different type of foreign particle.

• Primary : first antibody used in an immunoassay to detect the foreign particle; in this case, we are testing to see if the serum from the patients contains primary antibodies to SLE.
• Secondary antibody: the second antibody used in an immunoassay that detects the primary antibody. Note, this antibody must be made in a different species (rabbit, donkey, horse) than the primary antibody, in order to recognize the primary antibody as "foreign". In this case, we are using HRP-tagged rabbit anti-human antibodies as our secondary antibody.

Antibody-Enzyme Conjugate - antibodies (usually secondary antibodies) are "tagged" or joined to enzymes through a chemical process. Now the antibody is carrying an enzyme, so wherever the secondary antibody binds, the enzyme is present also.

Antigen - any substance (usually a protein or carbohydrate) that induces the production of antibodies by immune cells. Usually is a substance that is "foreign" to the host.

Antigenic Site - the part of the antigen that is recognized by the antibody

Assay - an examination or test

Centrifuge - an instrument used to spin tubes to separate solutions into different phases (liquid or solid). In this example, the red blood cells and other blood components are "spun out" of the blood, creating two layers in the tube: components below and serum above.

ELISA - Enzyme-Linked Immunosorbent Assay; this is an assay that uses an enzyme linked to an antibody. In this experiment, a colorless substrate is turned into a colored product by the bound enzyme. The amount of activity of this enzyme (as determined by detection of the amount of colored product) is used as a measurement of the amount of bound antibody.

Enzyme - a protein that acts as a agent or catalyst to induce chemical changes in other substances. An enzyme can be used repeatedly, because it is unchanged by the process.

Eppendorf® pipette - an instrument in the lab used to dispense small volumes of liquids (milliliters or microliters usually)

HRP - horseradish peroxidase; an enzyme used to stimulate the conversion of the colorless substrate into a colored product in this exercise

Humoral Immunity - this refers to the resistance that results from the presence of the specific antibody within the serum

Nanometers (nm) - a unit of measurement, in this case, one-billionth of a meter (10^-9 m)

Pipettor - a piece of equipment used to transfer a specified volume of a liquid

Sera/Serum - a clear watery fluid obtained after removing blood cells and other components from blood by centrifugation that will contain antibodies

Serial Dilutions - when the samples are diluted in a specific, systematic manner (1:2; 1:10; 1:100) to determine the concentration of a sample or the sensitivity of an assay

Spectrophotometer - an instrument for measuring the intensity of light of a specific wavelength transmitted by a substance. In this example, it will determine the amount of a reaction product which is absorbing the light in a solution.

Substrate - any substance on which an enzyme can act. In this example, HRP (the enzyme) will interact with a substrate called ABTS (2,2'-azinobis-3-ethylbenzothiazoleine-6-sulfonic acid) to produce a yellow solution.

Systemic Lupus Erythematosus (SLE) - Lupus is believed to be an autoimmune disease. The cause of lupus has yet to be determined. The immune system is your body's defense mechanism against foreign particles called antigens. Sometimes the immune system loses the ability to distinguish between its own body components and antigens. Instead of fighting antigens, the antibodies mistakenly fight the body's own cells. This is referred to as an autoimmune response (auto means self) and the body mistakenly makes autoantibodies. A systemic disease is one in which several different parts of the body may be affected. In systemic lupus, these include the skin, kidneys, nervous system, lungs, heart and/ or blood-forming organs.

Titer - the concentration of a substance in a solution. For instance, the amount of a specific antibody in the serum.