Intensive immunosuppression in patients with disseminated sclerosis. II. Tolerance to equine IgG and effect on immunoglobulin and complement levels.

Fourteen patients with multiple sclerosis were given two tolerizing doses of equine gamma-globulin before treatment with anti-lymphocyte globulin. Twelve patients had no clinical symptoms of hypersensitivity and most of them had no detectable antibody to the equine globulin until several months later. Even then, antibody could only be shown by immediate type skin reactions but not by any in vitro assay. We conclude that a state of partial tolerance was established in these patients for the period of treatment but that later they may develop traces of hypersensitivity.