Biochemical studies on the leukocytes in Chediak-Higashi syndrome.

Blood leukocytes from a patient with Chediak-Higashi syndrome (CHS) were compared with normal cells for their capacity of extruding (exocytosis) the lysosomal enzyme myeloperoxidase during phagocytosis or after a treatment with the ionophore A23187 and Ca2+. A decreased rate and extent of exocytosis in phagocytizing CHS cells was observed also with the Ca2+ ionophore. This suggests that a defect in Ca2+ mobilization is not responsible for the impaired secretion of granule content. Isolated granules of CHS cells and of leukocytes were treated with the detergent Triton X-100. Since the solubilization of myeloperoxidase from the CHS granules was much lower than from the normal ones, we suggest that the former organelles have a more resistant membrane.