McKenna's Pharmacology for Nursing, 2e

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C H A P T E R 1 7  Immune modulators

A s the name implies, immune modulators are used to modify the actions of the immune system. Immune stim- ulants are used to energise the immune system when it is exhausted from fighting prolonged invasion or when it needs help fighting a specific pathogen or cancer cell. Immune suppressants are used to block the normal effects of the immune system in cases of organ trans- plantation (in which non-self cells are transplanted into the body and destroyed by the immune reaction) and in autoimmune disorders (in which the body’s defences rec- ognise self-cells as foreign and work to destroy them) in some cancers. Each group acts at various sites within the immune response (Figure 17.1). The knowledge base about the actions and compo- nents of the immune system is continually growing and changing. As new discoveries are made and the actions and interactions of the various components of the system become better understood, new applications will be found for modulating the immune system in a variety of disorders. Box 17.1 discusses the use of immune modu- lators across the lifespan. Box 17.2 discusses use of these agents during pregnancy.

response to viral invasion; and interleukins, which are chemicals produced by T cells to communicate between leucocytes. I nterferons Interferons are substances naturally produced and released by human cells that have been invaded by viruses. They may also be released from cells in response to other stimuli, such as cytotoxic T cell activity. A number of interferons are available for use. Several are produced by recombinant DNA technology , includ- ing interferon alfa-2a ( Roferon-A ), interferon alfa-2b ( Intron A ), peginterferon alfa-2a ( Pegasys ), peginterferon alfa-2b ( Peg-Intron ) and interferon beta-1b ( Betaferon ). Interferon beta-1a ( Avonex ) is produced from Chinese hamster ovary cells. Interferon gamma-1b ( Imukin ) is produced by Escherichia coli bacteria. The interferon of choice depends on the condition being treated (see Table 17.1). Therapeutic actions and indications Interferons act to prevent virus particles from replicat- ing inside cells. They also stimulate interferon-receptor sites on non-invaded cells to produce antiviral proteins, which prevent viruses from entering the cell. In addition, interferons have been found to inhibit tumour growth and replication, to stimulate cytotoxic T-cell activity

IMMUNE STIMULANTS Immune stimulants (Table 17.1) include the interfer- ons, which are naturally released from human cells in

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FIGURE 17.1  Sites of action of the immune modulators.