Biomedical Engineering Reference
In-Depth Information
Table 8.2
Cytokines, as grouped on a structural basis
Cytokine family
Members
'
β
-Trefoil' cytokines
FGFs
IL-1
Chemokines
IL-8
MIPs
'Cysteine knot' cytokines
NGF
TGFs
PDGF
EGF family
EGF
TGF-α
Haematopoietins
IL-2-IL-7, IL-9, IL-13
G-CSF
GM-CSF
LIF
EPO
CNTF
TNF family
TNF-α and -β
As a consequence of the various approaches adopted in naming and classifying cytokines, it is
hardly surprising to note that many are known by more that one name. IL-1, for example, is also
known as lymphocyte activating factor (LAF), endogenous pyrogen, leukocyte endogenous me-
diator, catabolin and mononuclear cell factor. This has led to even further confusion in this fi eld.
During the 1980s, rapid developments in the areas of recombinant DNA technology and mono-
clonal antibody technology contributed to a greater depth of understanding of cytokine biology:
•
Genetic engineering allowed production of large quantities of most cytokines. These could be
used for structural and functional studies of the cytokine itself, and its receptor.
•
Analysis of cytokine genes established the exact evolutionary relationships between these molecules.
•
Detection of cytokine mRNA and cytokine receptor mRNA allowed identifi cation of the full
range of sources and target cells of individual cytokines.
•
Hybridoma technology (Chapter 13) facilitated development of immunoassays capable of de-
tecting and quantifying cytokines.
•
Inhibition of cytokine activity
in vivo
by administration of monoclonal antibodies (and, more
recently, by gene knockout studies) continues to elucidate the physiological and pathophysi-
ological effect of various cytokines.
The cytokine family continues to grow, and often a decision to include a regulatory protein in
this category is not a straightforward one. The following generalizations may be made with regard
to most cytokines:
•
They are very potent regulatory molecules, inducing their characteristic effects at nanomolar to
picomolar concentrations.
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