Proteinase inhibitors in cerebrospinal fluid in multiple sclerosis.

Levels of the proteinase inhibitors alpha 2-macroglobulin (alpha 2-m) and alpha 1-antitrypsin (alpha 1-at), and total protein, IgG and transferrin were measured in cerebrospinal fluid (CSF) from patients with multiple sclerosis (MS) and other neurological diseases. All groups except that termed "meningitis" had similar alpha 2-m levels, but alpha 1-at and transferrin were significantly depressed in MS. Total protein levels were normal and IgG levels were elevated in MS. Serum levels of alpha 1-at were normal so the decreases observed in the CSF in MS were not due to impaired systemic production. In view of previous reports that proteinase activity is high in MS plaques and CSF, the inhibitory capacity of alpha 2-m and alpha 1-at in CSF was measured. As any decreases in inhibitory capacity noted in MS were slight, they could only be important in the local environment of a plaque where enzyme levels may be critically high.