Treatment of chronic-relapsing experimental autoimmune encephalomyelitis with the synthetic immunomodulator linomide (quinoline-3-carboxamide)

Abstract

Linomide is a synthetic immunomodulator that enhances natural killer cell activity and significantly activates several lymphocytic cell subpopulations in both experimental animals and humans. In this study we examined the effect of linomide (80 mg per kg per day in drinking water) on mice with chronic-relapsing experimental autoimmune encephalomyelitis (CR-EAE), a T-cell-mediated organ-specific autoimmune disease that resembles human multiple sclerosis. None of the mice (n = 17) that were treated with linomide from day 7 after disease induction developed any clinical or histopathological signs of CR-EAE, as compared to 19 of 20 untreated controls that were severely paralyzed and had extensive demyelinating lesions in the central nervous system. Linomide-treated animals were also resistant to an induced attack by a booster injection with a murine spinal cord homogenate. When administered to mice exhibiting severe clinical signs of paralysis, linomide inhibited both spontaneous and induced relapses. Linomide treatment protected mice from passively induced CR-EAE as well, when given from the day of injection with myelin-basic-protein-specific lymphocytes. Lymphocytes obtained from linomide-treated mice had a reduced in vitro proliferative response to the myelin basic protein and to the tuberculin purified protein derivative, whereas the mitogenic response to concanavalin A was not affected. Natural killer cell and lymphokine-activated killer cell activities were enhanced. These results suggest that linomide regulates autoimmunity in the absence of systemic immunosuppression. Since linomide is very well tolerated in experimental animals and humans, it might be used in the treatment of multiple sclerosis.