Retrobulbar neuritis. In vitro evidence of sensitization to myelin basic protein in patients without multiple sclerosis.

Thirty-six normal subjects and 34 patients with retrobulbar neuritis were studied with use of the technique of macrophage migration inhibition factor assay and myelin basic protein as antigen. Serial studies were carried out when possible. Normal subjects gave a mean migration index of 100.9+/-9. Eleven patients with retrobulbar neuritis alone gave a mean migration index of 55+/-16 in the first 3 weeks of illness, 89+/-17.3 during the fourth to the twenty-fourth weeks, and 100.9+/-9.0 after the twenty-fourth week. Ten multiple sclerosis patients with retrobulbar neuritis gave values of 61+/-21 in the first 3 weeks of an attack and 92+/-22.8 during the fourth to the twenty-fourth weeks, and 12 other multiple sclerosis patients 24 weeks or longer after an attack gave a value of 101.9+/-12.6. In a mean follow-up period of 1.9 years, only two patients presenting with retrobulbar neuritis alone have had a diagnosis of multiple sclerosis established; three others have weakness and reflex change in one limb only; and four have minor psychiatric problems. One retrobulbar neuritis patient has a family history of multiple sclerosis, but has no neurologic abnormalities. Comparison of these studies in both groups shows no statistical differences and supports the concept that cell-mediated hypersensitization to central nervous system myelin basic protein, however initiated, is a factor in the pathogenesis of retrobulbar neuritis.