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.