An immunomodulator, also known as an immunotherapy is a substance (e. g. a drug) which has an effect on the immune system.
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Immune system can be modulated by the different ways with the use of:
Inhibits immune response in organ transplantation and autoimmune diseases.
Increase the immune response, useful in infections, immunodeficiency (for example, AIDS) and cancers.
Induces tolerance and makes the tissue non-responsive to antigen.
These drugs have major role in organ transplantation and auto immune diseases. The drugs are:
1. Calcineurin inhibitors (Specific T-cell inhibitors). Cyclosporine (Ciclosporin), Tacrolimus
2. Antiproliferative drugs (Cytotoxic drugs). Azathioprine, Cyclophosphamide, Methotrexate, Chlorambucil, Mycophenolate mofetil (MMF)
3. Glucocorticoids. Prednisolone and others
4. Antibodies. Muromonab CD3, Antithymocyte globin (ATG), Rho (D) immuneglobin, Efalizumab
They stimulate the immune system to fight against immunodeficiencies (like AIDS), infections and cancers.
1. Levamisole. An antihelmintic drug that also restores functions of B lymphocytes, T lymphocytes, monocytes and macrophages. Hence it has been used in colon cancer along with 5-FU.
2. Thalidomide. Different effects of this old drug have been utilized in conditions such as:
3. BCG. Used in carcinoma bladder.
4. Recombinant cytokines.
Induces tolerance and makes the tissue non-responsive to antigen. Tolerance is the state of non-responsiveness to antigen. The agents used as tolerogens are:
1. Costimulatory blockade. For activation, T lymphocytes need agonist specific signal from interaction of molecules such as CD28 on T lymphocytes and CD80 and CD86 on agonist presenting cell. Inhibition of this costimulatory signal can induce tolerance. Recombinant fusion protein molecules, anti CD50 MAB and anti CD56 MAB are acting by this mechanism.
2. Doner cell chimerism. Chimerism means the coexistence of two genetic lineages in a single individual. Immune functions of an individual are suppressed then a new source of immune functions like bone marrow is transfused. When it start functions, it does not recognize the antigen.
3. Soluble HLA. Human leukocyte antigen, induces tolerance through blood.
Most drugs however do not have effects on only one receptor, so an immunomodulator may be at the same time an immunosuppressant and an immunostimulant, on different targets within the immune system.
Products that are not single chemical entities, such as herbal extracts and impure products, may have even greater plurality of effect. Many species of plants, depending on the specific extraction conditions used, have immunomodulatory effects.[1]
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