Alpha 1-antitrypsin in cerebrospinal fluid of patients with neurologic diseases.

Proteases and their inhibitors have been implicated in the pathogenesis of neuroimmunologic diseases, particularly multiple sclerosis (MS). We measured the immunochemical level and functional activity of alpha 1-antitrypsin (AAT) in cerebrospinal fluid (CSF) and serum in patients with MS and other neurologic diseases. Increases in the immunochemical level of AAT in CSF correlated directly with disturbances in the blood-brain barrier, as reflected by the ratio of albumin in CSF to that in serum. The AAT activity in CSF directly correlated with the immunochemical level when all patients were compared. However, the AAT activity in patients with inflammatory diseases tended to be decreased relative to the immunochemical level, suggesting inactivation of AAT in these disorders. The AAT activity was not significantly altered in patients with MS, despite reports of increased protease activity in active MS.