Fig. 2.

Antibody titers to alglucosidase alfa and enzyme activity in plasma using doses of either 20 mg/kg or 40 mg/kg. Antibody titers to alglucosidase alfa over time in 20 mg/kg eow (a) and 40 mg/kg/week group (b). Peak antibody titers in relation to age at start of ERT. Patients received either 20 mg/kg eow (squares) or 40 mg/kg/week (asterisks) (c). Enzyme activity (d): blood samples were collected just before the start of infusion (0 h) and at regular time intervals thereafter. A dose of 20 mg/kg (circles) and 40 mg/kg (squares) were given to the same patient (patient 3) at 1 week interval after 5.5 years of therapy (titer 1:6250). Closed symbols represent total acid α-glucosidase activity in the plasma; open symbols represent the amount of activity that was not antibody-bound. The activity in the supernatant was measured with MUGlc and is expressed in nmol 4 MU liberated per 10 μl supernatant per hour. NB: Even though the enzyme-activity assay is a standardized and validated assay there is always a slight variation in the figures obtained. All samples were analyzed as part of one experiment. The total set of analyses were performed three times with comparable results