Impairment of calcium mobilization in phagocytic cells in glycogen storage disease type 1b

Patients with glycogen storage disease (GSD) type 1b, in contrast to patients with GSD 1a, are susceptible to recurrent bacterial infections suggesting defective phagocytic function. We have demonstrated a selective defect in respiratory burst activity but not in degranulation by phagocytic cells in GSD 1b but not in GSD 1a. The respiratory burst abnormality in phagocytic cells from GSD 1b patients was associated with impaired calcium mobilization, whereas these processes were normal in GSD 1a patients. Therefore, the alteration in calcium mobilization was an indication of a signalling defect in phagocytic cells from GSD 1b. However, calcium mobilization was normal in lymphocytes, indicating that defective calcium mobilization was not a global finding in circulating leukocytes, but was specific to phagocytic cells. Calcium mobilization in response to ionomycin was reduced suggesting decreased calcium stores in GSD 1b neutrophils. Therefore, altered phagocytic cell function in GSD 1b patients appears to be associated with diminished calcium mobilization and defective calcium stores. This defective calcium signalling was associated with a selective defect in respiratory burst activity but not degranulation.