Degradation of human myelin in vitro by leucocytes from patients with multiple sclerosis.

In order to study the possible autoimmune basis of multiple sclerosis (MS) a quantitative method has been used to investigate breakdown of human myelin in vitro. We found that serum from MS patients and controls was generally devoid of any myelin degradative activity. However, isolated peripheral blood mononuclear cells from 43% of MS patients showed significant myelin degradative activity as did those from 61.5% of patients with rheumatoid arthritis (RA). Myelin degradation by cells was found in only 13% of patients with other neurological diseases and in no healthy controls. It is proposed that this non-specific peripheral cellular immune degradative activity originates from cells activated within the central nervous system of MS patients or the joints of individuals with RA. As a result, activity in the blood only indirectly reflects the ongoing inflammatory response at the primary site, accounting for the lack of correlation between changes in the blood and the clinical status of the MS patient. We further propose that the lack of in vitro myelin degradative activity in cells recovered from the cerebrospinal fluid is due to autoaggressive cells being sequestered to the brain.