We have gathered here a list of the abbreviations used within the datasheets, along with a full name, a brief description of the technique, and in most cases a link to a Web page with a detailed description. Please contact us if there are abbreviations, assays, or useful Web links we have missed. For additional information, Wikipedia is usually a good source, and if you want a general educational overview of biology that is also very well cross-linked, try Kimball's Biology Pages, for instance this entry on monoclonal antibodies.

2DE	Two Dimensional Electrophoresis Two-dimensional gel electrophoresis (2-D gel electrophoresis) is used for detecting and analyzing hundreds to thousands of proteins with high resolution. The technology is a combination of isoelectric focusing (IEF) and polyacrylamide gel electrophoresis (PAGE). Proteins are first separated on the basis of their isoelectric point then on their molecular weight. Following the separation the gels may be stained and analyzed by image analysis, or detected by fluorescence or autoradiography. Alternately, the proteins can be transferred onto an immobilizing membrane and detected with specific reagents such as antibodies. More on gel blotting and Southern Blot from Kimball's online Biology text.
AC	Affinity Chromatography The isolation or purification of a protein by a separation process that uses a highly specific bioligand that has been immobilized on an inert matrix. The matrix is typically an agarose-gel bead, which is stable and to which the ligand is attached. An elution buffer is used, initially to wash away unbound proteins and then later at higher concentration or different pH to release the isolated protein from the ligand. Detailed discussion from Wikipedia. Simpler discussion, with diagrams, from Kimball's online. The use of tags in purification, from Bio-Medicine online.
AM	Antibody MicroArrays, Capture Arrays, Protein Arrays A fluorescence-based analysis in which covalently immobilized antibodies are used to capture fluorescent labeled antigens in order to compare two different samples with one another. Overview, from Wikipedia. Discussion from Functional Genomics. Antibody Array brochure from Clonetech.
BLOCK	Blocking antibody An antibody that combines with an antigen without a reaction but that blocks another antibody from later combining with that antigen.
CE	Capillary Electrophoresis The use of small capillaries for electrophoresis allows for higher electromagnetic fields because the fine capillaries are very efficient at dissipating the heat generated. The use of stronger fields means quicker resulta and very efficient separations. General description from Wikipedia. Introductory overview from Davidson College. Primer from Beckmann Coulter.
ChIP	Chromatin immunoprecipitation   ChIP is a type of immunoprecipitation experimental technique used to investigate the interaction between proteins and DNA in the cell. It aims to determine whether specific proteins are associated with specific genomic regions, such as transcription factors on promoters or other DNA binding sites, and possibly defining cistromes. ChIP also aims to determine the specific location in the genome that various histone modifications are associated with, indicating the target of the histone modifiers. General description from Wikipedia.
CIE	Countercurrent Immunoelectrophoresis One-dimensional double electroimmunodiffusion; a technique in which antibody and antigen are placed in separate wells in an agar plate and driven toward each other by an applied electric field, because the gel is buffered at a pH between the isoelectric points of the antigen and antibody. It is more sensitive and faster than double immunodiffusion (DID) and is particularly useful for antigens that diffuse slowly in the gel. Also called Counterimmunoelectrophoresis or Counterelectrophoresis.
CM	Confocal Microscopy The confocal microscope uses pinholes, or apertures, to exclude out-of-focus light from an image. Only light from the plane of focus is collected and stored as a digital image. This image is referred to as an "optical section". Many of these sections can be collected and reconstructed into a three dimensional object. Specimens are probed with fluorescent probes for viewing (see IF). Detailed description from Emory University.
Crossed IEP	Crossed immunoelectrophoresis A combination of protein electrophoresis (EP) and rocket immunoelectrophoresis; protein antigens are separated by agarose gel electrophoresis; then a strip containing the separated antigens is cut out and placed in a trough in a gel containing antiserum, and an electric field perpendicular to the trough is applied, producing a "rocket" precipitin pattern for each antigen. Also called Laurell's first technique. Immunoelectrophoresis and crossed immunoelectrophoresis with images. Immunoelectrophoresis and crossed immunoelectrophoresis from Wikipedia. An early example from the literature.
DB	Dot Blotting The dot blot is a quick and dirty technique that skips the chromotography of other blot methods, and deposits the biomolecules to be measured directly onto the membrane as a dot, followed by detection by neucleotide probes or antibodies. The pros and cons from Wikipedia. Detailed protocol from Millipore. Analysing a dot blot image, from NIH. Extensive list of references from Antibody&Beyond.
DID or IDD or ID	Double immunodiffusion or Immuno double diffusion, Ouchterlony, or Immunodiffusion A technique designed to establish the identity of unknown protein samples based on the interaction between antibodies and antigens in solution. Anti-serum, antigens, and/or an unkown substance are each placed into separate wells and allowed to diffuse radially outward through an agarose gel. As the expanding rings come in contact with each other, insoluble antigen/antibody complexes precipitate out of solution forming readily recognizable patterns. An overview from Wikipedia. Details and protocol from Universitie Pierre & Marie Curie (translated). Some images of immunodiffusion gels from National Diagnostics.
EIA	Enzyme Immunoassay Same as RIA except that the ligand is labeled with an enzyme instead of with a radioactive tag. Usually equivalent to ELISA. Concept, history and references from Marquette University.
ELIFA or ELFA	Enzyme-linked Immunofluorescent Assay A variety of EIA in which a flourescent compound is used to indicate the presence of the antigen.
ELIFA	Enzyme-linked Immunofiltration assay A fast, high-throughput assay. The method derives from the enzyme-linked immunosorbent assay but is performed on filtration membranes which allow the retention of particles for subsequent immunoenzymatic analysis. With this technique antigen-antibody binding is accelerated by the filtration of the antibody solution through the antigen-coated nitrocellulose filter instead of its remaining over the solid phase for incubation. A comparative evaluation of ELIFA and ELISA, article from Wiley Interscience.
ELISA	Enzyme-linked Immuno Sorbant Assay ELISA typically involves a two-stage incubated immuno reaction. First the target antigen binds with a solid phase antibody. Non-bound materials are washed away and an enzyme-labeled antibody, called a conjugate, binds to form a 'sandwich' complex. Finally the antigen-antibody is introduced to a substrate where a chromogen is used to give a color change indicating the presence of the antibody. An extensive overview from Wikipedia. A stepwise tutorial with graphics and animations from The Biology Project, University of Arizona.
EMSA	Electrophoretic Mobility Shift Assay EMSA is used to detect the interaction of DNA binding proteins with their DNA recognition sequences, and has been extended to allow detection of RNA binding proteins. Purified proteins or crude cell extracts are incubated with a radiolabelled DNA or RNA probe. The complexes are separated from the free probe by migration through a nondenaturing polyacrylamide gel, with the complexes migrating more slowly. High-level overview from Wikipedia. A detailed protocol from Open Wetware. Another example (for NFκB) with a detailed protocol from the apoptosis website, Celldeath.de. Description of Chemiluminescent EMSA from Thermo Scientific.
EP	Electrophoresis EP is used to separate a complex mixture of proteins with respect to the presence or other characteristics of one or more proteins to which they bond. The separation is through migration of the charged molecules across a support medium and in response to an electric field. The medium is typically a gel but may be paper, potato starch, cellulose acetate, agarose or polyacrylamide gel; the last two gels are the most commonly used media. Agarose is usually made into dilute gels for separating large macromolecules, proteins and protein complexes. Polyacrylamide gels (see PAGE) are used at higher concentrations, to separate most proteins and small oligonucleotides. Proteins of known molecular weight are often included in the initial mixture, to serve as calibrating markers. Thorough discussion from Wikipedia.
ESA	Electromobility Shift Assay See EMSA
FC or FACS	Flow Cytometry or Fluorescence Activated Cell Sorter FC is a method of quantifying components or structural features of cells by optical means, and often uses fluorescent labeling. Cells in single-cell suspension are flowed rapidly single-file through a laser beam. Each cell scatters some of the light, and labeled cells emit flourescent light excited by the laser. Cell size and granularity can be measured from the scattered light, and flourescent intensities measure the quantities of particular cell components. Thorough discussion from Wikipedia. A tutorial from UC Berkeley, with powerpoint and a discussion of Flourescence Compensation. Extensive webset of pages from the FC center at the Walter and Eliza Hall Institute, Australia.
FISH	Fluorescent In-Situ Hybridization The hybridization reaction identifies, or labels, target genomic sequences so their location and size can be studied. DNA or RNA sequences from appropriate, chromosome-specific probes are first labeled with reporter molecules, which are later identified through fluorescence microscopy. The labeled DNA or RNA probe is then hybridized to the metaphase chromosomes or interphase nuclei on a slide. After washing and signal amplification, the specimen is screened for the reporter molecules by fluorescence microscopy. Overview from Wikipedia. Flowchart-driven discussion from Davidson College, with many links out. Outline from the Pasteur Institute, with discussion of random priming. Review with emphasis on microscopy.
Gel MSA	Gel Mobility Shift Assay see EMSA.
IB, IEB	Immunoblotting, Immunoelectroblotting A general term for Western blots, Northern blots, dot/slot blots, etc. After a gel separation the immobilized proteins are transferred to a filter paper or blotting paper via a sandwich involving the gel, nitrocelulose paper/blotting paper, and filter paper, either by electrophoresis under a low current for 20-30 minutes or by capillary blotting from wet to dry filter paper. The three popular blotting methods are Southern Blot, for DNA cut with restriction enzymes and probed with radioactive DNA, Northern Blot, for RNA probed with radioactive RNA or DNA, and Western Blot, for proteins (antigens) probed with proteins (antibodies).
IC	Immunocytochemistry The use of antibodies to detect proteins within cells, typically cells isolated from their surrounding media. Often the antibodies are bound with electron-opaque markers, so as to visualize the proteins under an electron microscope. Typically the cells are embedded or frozen, then sectioned and labelled with antibodies and markers. General overview from Wikipedia. More details from IHC World.
IEP	Immuno-electrophoresis IEP is a name for several techniques all involving separation of proteins by electrophoresis and the use of immunoglobulins (antibodies) to react with the proteins. Typically agarose gel is used. See also Crossed immunoelectrophoresis (CIE) and Rocket immunoelectrophoresis (Rocket IEP). Broad overview from Wikipedia. Immunoelectrophoresis and the major immunoglobulins, from Protocol Online.
IF	Immunofluorescence The use of a fluorescene conjugated antibody or secondary antibody to visualize an antigen when viewed under a microscope or flow cytometer. For fluorescent microscopy, the specimen is fixed to a slide and then the flourescent labelled antibody (primary or secondary) is added and the mixture is incubated, rinsed and examined with a fluorescent microscope using filters appropriate for excitation and emission of the particular fluorochrome, can also be used with confocal microscopy (see CM). For FAC, single cell suspensions are fixed in solution and then a fluorescent-labeled antibody is added. The mixture is inserted through a flow cell and each cell scatters some of the light, and labeled cells emit fluorescent light excited by the laser beam. Results are recorded as peaks and scatter lines corresponding to wavelenth (see FAC). Brief description with rationale and link for GFP, from Wikipedia. Straightforward example from Davidson College. Discussion of microscopy aspects, from Antibody Station.
IFE	Immunofixation Electrophoresis IFE combines zone electrophoresis with immunoprecipitation. This technique may be used to identify and characterize serum proteins. In IFE, proteins of sample are first separated by electrophoresis on a support (agarose) according to their charge and after that the medium is overlaid with monospesific antisera reactive with specific protein - antigen. If the antigen is present a characteristic immunoprecipitin band will form. Discussion of Immunofixation from Wikipedia. IFE with Cellulose acetate IFE uses a cellulose acetate strip, impregnated with antiserum, over the gel after electrophoretic migration has taken place. After diffusion of the antiserum from the strips to the gel and precipitation of antigen-antibody complexes, the precipitin bands are stained.
IHC, IH	Immunohistochemistry IHC is the process of staining tissues with antibodies and developing the result with histologic labels such as enzymes or fluorochromes. The tissues are rapidly frozen [IH(F)] or fixed and embedded [paraffin IH(P)], then sectioned, stained and examined under a light or fluorescent microscope. The antibodies are labeled with enzymes or fluorescent tags, either by directly conjugating the antibody or by using tagged secondary antibodies. The enzymes labeled specimens are developed with a dye. It is possible to develop the specimens with more than one antibody by using different colored dyes or different fluorochromes having different wavelengths. See also Immunofluorescence (IF) Broad and thorough overview from Wikipedia. A more extensive presentation from an IHC-oriented website, IHCWORLD.
IHC(F), IH(F)	Immunohistochemistry, Frozen sections See Immunohistrochemistry (IHC) Many protocols are available online.
IHC(P), IH(P)	Immunohistochemistry, Paraffin sections See Immunohistrochemistry (IHC) Many protocols are available online.
IP	Immunoprecipitation When an antibody has multiple binding sites, each specific to a separate epitope, an antibody, antigen chain may form which grows to be heavy enough to precipitate out of the solution. Applications of imunoprecipitation can be be for immunodiffusion (DID, ID) and for Immunoblotting (IB). Thorough description from Wikipedia. Discussion with binding table for immunoglobulins, from eBioscience.
IS	Inhibition Studies An immunoassay in which an excess of antigens prevents or inhibits the completion of either the initial or the indicator phase of the reaction. 1. Competitive inhibition: inhibitor molecules resemble the substrate molecules and bind to the active site of the enzyme, so preventing normal enzymatic activity. Competitive inhibition can be reversed by increasing the concentration of the substrate. 2. Non-competitive inhibition: inhibitor binds to a part of the enzyme or enzyme-substrate complex other than the active site. 3. Feedback inhibition: An inhibition of activity due to the production of an end product of the action. Also called feedback mechanism.
ISH, ISHH	In-Situ Hybridization Histochemistry ISH allows cell-specific localization of RNA or DNA sequences in tissue sections or on a chromosome. Tissue sections are incubated overnight under the appropriate conditions with labeled nucleic acid probes that specifically 'hybridize' to the RNA or DNA of interest. The tissue sections are then washed under low salt and high temperature conditions to reduce the amount of non-specific hybridization. The sections are then either apposed to x-ray film (in the case of radio-labeled probes), or immunohistochemically treated to detect hybridized probe and to quantify the amount of RNA in a particular section (see FISH). Overview and protocols from the internal research division of the NIMH. Understanding the 'in situ' principle, from Davidson College.
MgB	Magnetic beads Magnetic particles present one intriguing way of cell sorting. Antibodies specific for a particular cell of interest are covalently bound to magnetic particles. A mixture of cells in solution are mixed with the magnetic antibodies. The entire reaction mixture is exposed to a magnetic field, which retains the cells of interest. Removing the magnet frees the cells again. History and applications for Dynal® beads from Invitrogen.
MxA	Multiplex Arrays Capture antibodies are spotted on the well surface of either 96- or 384-well plates. Each arrayed antibody captures specific proteins present in both the calibrated standards and the unknown samples added to the plate. The bound proteins are then quantitated using a biotinylated detection antibody, followed by the addition of streptavidin-horseradish peroxidase (HRP) and lastly, a chemiluminescent substrate. The luminescent signal is measured using a CCD plate imager. Description of protein microarrays from Wikipedia.  . Measuring performance of multiplex bead arrays, from NIH researchers.
Neut	Neutralization antibody An antibody that binds to specific antigens or receptors and thus prevents infectious agents from infecting cells.
NIA	Nephelometric Immunoassay Uses a monospecific anti-IgG subclass specific antiserum and the human IgG subclass to be determined. The generated immune complexes are quantified by measuring the side-scattered laser-light shining through the solution. There must be enough extra antibody in solution so that small complexes form but immunoprecipitation does not occur. Nephelometry measures soluble antigen-antibody complexes, and has replaced radial immunodifusion (RID) in many applications. Definition of nephelometry from Wikipedia. Example of a Rate Nephelometric Assay of Lipoprotein(a) from Clinical Chemistry.
PAGE	Polyacrylamide Gel Electrophoresis Separation of proteins by their relative migration across a polyacrylamide gel medium in an electric field. PAGE and gel electrophoresis in general are used for: determination of molecular size, approximate weight and purity of proteins, determination of number and size of subunits, determination of carbohydrate content, and isolation and recovery of individual proteins from complex mixtures. A detailed SDS-PAGE discussion from Wikipedia. An animation from Cold Spring Harbor Laboratory.
RIA	Radio Immunoassay In this highly sensitive test a radioactive isotope is bound to the antigen and the amount of antigen is quantified by a gamma-ray counter. The antigen is initially bound to the walls of a test tube or microplate, serum is added which binds to the antigen and the bound antibody is detected by adding a radiolabeled ligand. The addition of various concentrations of unlabeled ligand and the measurement of the various ratios of bound labeled to free labeled ligand produces a calibration curve for determining the ligand concentration. A description and process diagram from Kimball's online Biology text.
RID, SRID	Radial Immunodiffusion, Single Radial Immunodiffusion Method for obtaining a precipitate between an antibody and its specific antigen by suspending one in a gel and letting the other migrate through it from a well. Multiple wells are often used. See Immunodiffusion (ID) Note: sometimes Single Radial Immunodiffusion is used to mean Ouchterlony. A description and protocol from Immunohistochemistry Protocols.
RIP	Radio-immunoprecipitation Sensitive assay using radiolabeled antigens to detect specific antibodies in serum. The antigens are allowed to react with the serum and then precipitated using a special reagent such as Protein A sepharose beads. The bound radiolabeled immunoprecipitate is then commonly analyzed by gel electrophoresis. Comparison of RIP and Elisa, paper from Johns Hopkins.
Rocket IEP	Rocket Immunoelectrophoresis One-dimensional single electroimmunodiffusion; a technique in which antigen is placed in a row of wells in an agar plate containing antiserum and an electric field perpendicular to the line of wells is applied; this drives the antigen through the gel, forming a spike or "rocket" precipitin pattern trailing away from each well. The length of the rocket is proportional to the amount of antigen placed in the well. Called also Laurell's second technique. See IEP. Details from The Protein Protocols Handbook.
TMA	Tissue Microarray or Tissue Array or Tissue Chips Like NIA, TMA is based on detection of fluid-phase antigen complexes, but TIA works by measuring the decrease in light transmission rather than the side scattering of the light. See NIA. Overview from Yale School of Medicine. How to choose a tissue microarray, from the Tissue Microarray Organization. Varieties of tissue microarrays, from Microarray Station.
TIA	Turbidimetric Immunoassay Like NIA, it is based on detection of fluid-phase antigen complexes, but TIA works by measuring the decrease in light transmission rather than the side scattering of the light. The reduction of light intensity results from a combination of reflection, absorption and scattering of the incident light. The light source is typically in the near ultraviolet range, and the technique is limited primarily by the accuracy of the measuring device. See NIA.
WB	Western Blot The common means for probing proteins with radioactive or enzymatically-tagged antibodies after they have been spatialy separated and immobilized, typically on an agarose or poly-acrylamide gel (see IEP), and transfered to a filter paper or blotting paper through electrophoresis or capillary blotting. The antibody probe is typically enzyme-conjugated by cross-linking to the enzyme, and is added to the paper in buffer and incubated for several hours. Extra probe is washed away, and the filter paper is then soaked in a solution that is a substrate for the enzyme and results in an insoluble colored deposit. Detailed description from Wikipedia.