Plasmapheresis combined with interferon: an effective therapy for multiple sclerosis.

The rationale for the use of interferon (IFN) in the treatment of multiple sclerosis (MS) is based on its recognized antiviral and immunomodulating actions. The pathogenesis of MS is believed to be due to an immunologic response in a genetically predisposed individual, localized within the central nervous system white matter, and triggered by exposure to an environmental agent such as a virus. Based on our personal experience we find that the efficacy of IFN therapy is hampered in MS patients by the presence of an interferon inhibitor factor (IIF) in the patients' sera which we have isolated and characterized. When plasmapheresis (PP) was done on 24 MS patients with intermittent 3-day administration of IFN-alpha and human leukocyte IFN, marked increase of IFN in 18 patients and modest increase in three patients correlated with clinical improvement. Three clinical nonresponders showed no increase in IFN levels following therapy. The ability to remove IIF and lymphokine inhibitor factor (LIF) by PP may explain the successful treatment of our patients. We describe the evaluation of helper T cells, suppressor T cells, HLADR antigen, natural killer cells, and monocyte/macrophage cell populations by flow cytometry before and after PP. A significant increase in these immune-competent cells correlated with marked improvement in Kurtzke disability status scale in 13 patients, while eight stabilized. Patients showing progression of the disease either showed decrease or no change in these parameters after therapy. Encouraging results from this pilot study suggest that PP combined with immunomodulatory regimens of IFN may be an effective therapy for MS.