2008 PBL Cat_mech_r.qxd:PBL Catalog.mech 11/29/07 1:51 PM Page 53
Glossary
Heterophilic Antibodies Interference Antibodies present in the host that bind to animal antibodies used in an immunoassay and thus produce erroneous results.
Histogram A one-parameter histogram is a graph of cell count on the Y-axis and the fluorescent intensity on the X-axis.
Horseradish peroxidase (HRP) The enzyme horseradish peroxidase (HRP), found in horseradish, is used extensively in molecular biology and in antibody
amplification and detection. In ELISA color development, HRP has been known to produce superior sensitivity over Alkaline
Phosphatase (AP), primarily due to the faster catalytic rate of HRP and thus more color is generated in a shorter period of
time. However, with the increase of sensitivity, HRP reaction products fade quickly. Additionally, the co-substrate of the
reaction, H
2
O
2
, can limit the activity of HRP and shorten the linear incubation period. Therefore, it is imperative to
determine the OD values at 450nm within a short period of time (15-20 minutes) after the substrate reaction has been
stopped. Other factors such as temperature and molarity of the buffer also affect the performance of HRP.
International Unit The quantity of interferon necessary to produce a cytopathic effect of 50%. The units are determined with respect to the
international reference standard provided by the National Institutes of Health. It is generally recognized that using the same
reference standard will reduce, but not eliminate, the variability in specific activity determination from laboratory to laboratory.
Therefore, even if two IFN products whose specific activities are the same, differences in antiviral and other biological activities
may still exist.
Janus kinase (JAK) Janus kinase (JAK) is a family of intracellular non-receptor tyrosine kinases that transduce cytokine-mediated signals via the
JAK-STAT pathway.
Major Histocompatibility The Major Histocompatibility Complex (MHC) is a set of molecules displayed on cell surfaces that are responsible for
Complex (MHC) lymphocyte recognition and “antigen presentation”. The Class I and Class II MHC molecules belong to a group of molecules
known as the Immunoglobulin Supergene Family, which includes immunoglobulins, T-cell receptors, CD4, CD8, and others.
Monoclonal Antibodies Immunochemically identical antibodies that bind to a specific epitope on a given antigen
Neutralizing Antibodies Neutralizing antibodies are a subset of Binding Antibodies, which have the ability to inhibit the biological activity of an antigen.
If IFN has been neutralized, there is no protection to the cell and the virus kills the cells. However, one (1) neutralizing unit of
MAb for IFN-αonly neutralizes 90% of IFN, the remaining 10% of IFN can still have protective ability. Therefore, one must use
more MAb to make sure that all IFN-αis neutralized. Furthermore, particular cell lines may also have IFN-βor IFN-γthat can be
protective as well. Researchers need to be aware which cell lines they are using and whether they have protective features
other then IFN-α.
p38 MAPK The p38 MAPK (MAPK14) exists as four distinct isoforms in humans; p38α, p38β/β2, p38γand p38δ. The p38αisoform has
been shown to be required for up-regulation of type I IFN (but not type II) gene expression. Consequently, p38αMAPK is
required for the robust antiviral properties of type I inteferons.
R-Phycoerythrin (RPE) R-phycoerythrin is a phycobiliprotein derived specifically from red algae. RPE-labeled antibodies are used extensively in
fluorescent immunoassays and flow cytometry applications.They are also ideal for use in multiple labeling with other
fluorochromes: RPE and FITC can be used for double labeling in flow cytometry using a single excitation line.
Polyclonal Antibodies A mixture of immunochemically different antibodies that can recognize multiple epitopes on a given antigen
Specific Activity The specific activity of interferon can be determined with the use of the cytopathic effect assay. In this antiviral assay, about 1
unit/mg is the quantity necessary to produce a cytopathic effect of 50%. The units are determined with respect to the
international reference standard for human interferon alpha A(IFN-αA) provided by the National Institutes of Health [see
Pestka, S. (1986) "Interferon Standards and General Abbreviations," in Methods in Enzymology (S. Pestka, ed.), Academic
Press, New York 119, 14-23].
Signal transducer and activator of Signal transducer and activator of transcription (STAT) proteins are a 7-member family of cytoplasmic transcription factors that
transcription (STAT) contribute to signal transduction by cytokines, hormones, and growth factors. STAT1 promotes signaling of several cytokines
including type I and type II interferons through the JAK-STAT pathway. STAT3 is an intracellular protein that exists in two distinct
isoforms, full length STAT3α(86kDa) and STAT3β(79 kDa). Many cytokines (IL-6, IFNs) and growth factors (p38 MAPK, ERK1
& 2) with vastly different biological functions have been shown to participate in the activation of STAT3 by promoting
phosphorylation of the protein at Tyr705 and Ser727, respectively.
Toll Like Receptors (TLRs) TLRs are a type of pattern recognitionreceptor(PRR) and recognize molecules that are broadly shared by pathogens but
distinguishable from host molecules, collectively referred to as pathogen-associated molecular patterns (PAMPs).
Tumor necrosis factor-alpha (TNF-α) Mouse TNF-α, also known as cachectin, is a glycoprotein composed of 156 amino acids produced mainly by monocytes and
activated macrophages. TNF-αhas been shown to possess tumoricidal activity as well as a variety of physiologic effects with
most major organ systems.
www.interferonsource.com Tel: +1 732-777-9123
I
Fax: +1 732-777-9141
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