Biomedical Engineering Reference
In-Depth Information
•
Listeria monocytogenes
, a bacterium that, when transmitted to humans, causes listeriosis. Lis-
teriosis is characterized by fl u-like symptoms, but can cause swelling of the brain and induce
abortions.
•
Legionella pneumophila
, the bacterium that causes legionnaire's disease.
The immunological response raised against intracellular pathogens is largely a T-cell response.
IL-2's ability to stimulate T-cells may render it useful in the treatment of a wide range of such
conditions. Clinical trials assessing its effi cacy in treating a range of infectious diseases, includ-
ing AIDS, continue. A related potential medical application of IL-2 relates to its possible use as
adjuvant material in vaccination programmes (Chapter 13).
9.2.4 Safety issues
Like all other cytokines, administration of IL-2 can induce side effects that can be dose limit-
ing. Serious side effects, including cardiovascular, hepatic or pulmonary complications, usually
necessitate immediate termination of treatment. Such side effects may be induced not only
directly by IL-2, but also by a range of additional cytokines whose synthesis is augmented by IL-2
administration. These cytokines, which can include IL-3, -4, -5 and -6, as well as TNF and IFN-
,
also likely play a direct role in the overall therapeutic benefi ts accrued from IL-2 administration.
γ
9.2.5 Inhibition of interleukin-2 activity
A variety of medical conditions exist that are caused or exacerbated by the immune system itself.
These are usually treated by administering immunosuppressive agents. Examples include:
•
Autoimmune diseases in which immunological self-tolerance breaks down and the immune
system launches an attack on self-antigens.
•
Tissue/organ transplantation in which the donor is not genetically identical to the recipient
(i.e. in cases other than identical twins). The recipient will mount an immune response against
the transplanted tissue, culminating in tissue rejection unless immunosuppressive agents are
administered.
Selective immunosuppression in individuals suffering from the above conditions is likely best
achieved by preventing the synthesis or functioning of IL-2. Cyclosporin A, one of the foremost
immunosuppressive agents currently in use, functions by preventing IL-2 synthesis. A number
of alternative approaches are now being considered or tested directly in clinical trials. These
include:
•
Administration of soluble forms of the IL-2 receptor, which would complete with the native
(cell surface) receptor for binding of IL-2.
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