Enzyme immunoassay of medullasin in peripheral blood.

An enzyme immunoassay method for the determination of the amount of medullasin, a serine protease in granulocytes, was developed. Beads coated with IgG obtained from immunized rabbits were incubated with medullasin, Fab'-peroxidase conjugate was added, and peroxidase activity bound to beads was measured by a fluorophotometer. The amount of medullasin determined by this method correlated well with the value calculated from the protease activity measured by the conventional method. The minimum detectable amount of medullasin was 300 pg. Granulocytes obtained from patients with multiple sclerosis in active phase and those from patients with Behçet's disease in relapse showed elevated levels of medullasin as compared with normal controls. However, the amount of medullasin in granulocytes obtained from patients in remission revealed normal values. These results indicate that elevated levels of medullasin activity in granulocytes of these diseases in relapse is due to an increased amount of medullasin in granulocytes and that the normalization of medullasin activity in remission is the result of the decrease of the amount of medullasin in granulocytes.