A recent overview on in vitro and in vivo immunological activities of methisoprinol.

Methisoprinol (Isoprinosine), a purine derivative, has been shown to exert a number of immunopharmacological effects, both in vitro and in vivo, in animal and human studies. The agent, somehow mimicking the effects of thymic factors, induces the appearance of phenotypic markers of differentiation on immature precursor T cells; enhances the proliferative response of murine and human lymphocytes to mitogens or antigens, augments helper or suppressor T cell functions and increases the production of lymphotoxin a lymphokine. It has also been shown that this drug can potentiate the effects of macrophage activating factor to stimulate macrophage, and of interferon to protect mice against experimental viral and tumor challenges. In humans, beneficial results have been reported from clinical trials testing the effects of methisoprinol in a variety of diseases including subacute sclerosing panencephalitis (SSPE), acute viral encephalitis, recurrent mucocutaneous infections due to type I and II Herpes viruses as well as in immune restoration of cancer patients with immunodepression following radiotherapy. The drug is also being studied in immunopathological disorders such as rheumatoid arthritis, systemic lupus erythematosus. Sjogren's disease and type A hepatitis. The large spectrum of effects of methisoprinol on a number of immune parameters, the increasing evidence of its therapeutic value in several pathological conditions and its safety of use qualifies this drug as an interesting immunoregulating agent.