Polymorphonuclear neutral protease activity in multiple sclerosis and other diseases.

Polymorphonuclear neutral protease activity (PMN-NPA) was examined in 87 patients with definite multiple sclerosis (MS) (48 active, 39 inactive), 49 patients with other neurological diseases (OND), 24 patients with immune-mediated non-neurological diseases (INND), and 32 normal subjects. PMN-NPA was found to be significantly increased in active MS compared with inactive MS and compared with each of the control groups. No differences were found between the group of normal subjects and the groups of patients with OND, INND, or inactive MS. Levels of PMN-NPA were significantly higher in the OND group than in inactive MS group. The differences for INND versus normal controls, neurological controls, and patients with inactive MS were not significant. No significant differences have been detected between active and inactive INND. These results suggest that PMN-NPA may be useful in the diagnosis and evaluation of MS.