Normal-sized primary lysosomes are present in Chediak-Higashi syndrome neutrophils.

Azurophil granules of normal neutrophils are known to be primary lysosomes and contain myeloperoxidase activity. The present study has used ultrastructural cytochemistry to selectively stain myeloperoxidase containing granules of normal and Chediak-Higashi syndrome neutrophils and serial thin sections to determine if all peroxidase-positive organelles in Chediak-Higashi syndrome cells are protrusions of the huge inclusions characteristic of the disorder. Peroxidase-positive organelles in polymorphonuclear leukocytes from three patients with Chediak-Higashi syndrome varied in size from vesicles and normal-sized lysosomes to the huge bodies filling the cytoplasm. Serial sections demonstrated that the small and normal-sized organelles were commonly present and independent of the giant granules. One type of the normal-sized lysosomes contained small vesicles free of peroxidase activity, conveying a honeycomb-like appearance to the matrix. This variety, in particular, was identified in various stages of fusion with giant organelles in circulating Chediak-Higashi syndrome neutrophils.