Studies of protease inhibitors in the sera of patients with amyotrophic lateral sclerosis.

Serum levels of 4 protease inhibitors, alpha-1-antitrypsin, C1-inactivator, alpha-2-macroglobulin and antithrombin-III were measured in 11 patients with amyotrophic lateral sclerosis (6 males and 5 females) and a control group without neurologic disease. Our results indicated no significant differences in the level of serum alpha-2-macroglobulin between the 2 groups. We found slight but significantly lower levels of serum antithrombin-III in ALS. The possibility of the participation of proteases or protease inhibitors in the pathogenesis of ALS is discussed.