Reduced 2',3'-cyclic nucleotide 3'-phosphohydrolase activity in erythrocyte membranes of patients with multiple sclerosis.

2',3'-Cyclic nucleotide 3'-phosphohydrolase (CNPase) activity is reduced in myelin during multiple sclerosis. Therefore, we have investigated whether the enzyme is also depressed in non-neural membranes during this disease. MS and control erythrocyte membranes and whole lymphocytes were assayed for CNPase activity. The MS erythrocyte membrane preparations were found to exhibit up to 45% lower CNPase levels than the controls (P less than 0.02). There was no significant difference in the lymphocyte CNPase levels in MS and control groups. When control erythrocyte membrane preparations were assayed in the presence of MS plasma they were inhibited 100% by MS (but not by control) plasma. These data suggest that erythrocyte membrane CNPase activity is significantly reduced in MS patients and that the reduction in activity may be due to an inhibitor present in MS plasma.