Antibody response in patients with Gaucher disease after repeated infusion with macrophage-targeted glucocerebrosidase.

Recent clinical data have shown that enzyme replacement therapy with macrophage-targeted glucocerebrosidase (GCR) can be effective in treating type 1 Gaucher disease. Sera from 262 patients, repeatedly infused with GCR, were assessed for the presence of antibodies to this therapeutic protein. Patient serum samples obtained at 3-month intervals were assessed by enzyme-linked immunosorbent assay and those with values greater than two standard deviations above the mean value obtained with a pool of normal human sera were further characterized by radioimmunoprecipitation. At the time of these analyses, the duration of patient treatment varied from 3 months to approximately 3 years. Of the 262 patients analyzed, 34 (12.9%) showed IgG antibodies, as confirmed by radioimmunoprecipitation. All patients who seroconverted did so within 1 year of treatment. The predominant antibody developed was the IgG1 subclass. Fourteen patients in the study experienced periodic symptoms suggestive of immediate hypersensitivity. Nine of these 14 patients had antibody to GCR as determined by radioimmunoprecipitation, whereas 5 patients were antibody negative. There was no evidence of the development of IgE antibodies in these 14 patients. The presence of GCR antibodies did not appear to effect efficacy of therapy in any of the patients treated to date.