Significant increase in immunosuppressive acidic protein (IAP) in serum of patients with multiple sclerosis and other inflammatory neurological disorders

Abstract IAP, a type of α 1 -acid glycoprotein, is mainly produced by macrophages when stimulated in the presence of circulating immune complexes or some inflammatory substances. We assayed the serum levels of IAP by a single radial immunodiffusion method. The normal level of IAP is below 500 μg/ml (385 ± 73). In multiple sclerosis patients, however, IAP increased during exacerbation (630 ± 191) and decreased during the inactive stage (433 ± 170). Eighty-five percent of patients with neuro-Behcet's disease also had high levels of IAP, correlating well with disease activity. In some patients with Guillain-Barre syndrome or Miller Fisher syndrome, IAP increased during the acute phase. In patients with herpes simplex encephalitis, IAP levels remained abnormally high for more than 60 days after onset. The mean value of IAP in patients with amyotrophic lateral sclerosis did not differ from that of normal controls. An increase in IAP in the serum of patients seems to reflect the activity of an inflammatory or immunopathological process.