Chediak-Higashi syndrome. Light micrograph of blood cells in a case of Chediak-Higashi syndrome. The cells include neutrophil white blood cells with abnormal granules, and a promyelocyte (upper centre) with a large azurophilic inclusion in a vacuole. An azurophilic granule (azurophil) or inclusion is one that takes up stains with an azure (dark red) colour. A promyelocyte is a precursor cell that develops into a granulocyte such as a neutrophil. White blood cells are part of the body's immune system. Chediak-Higashi syndrome is a genetic disorder that leads to a reduction in phagocytosis by white blood cells, increasing susceptibility to infections.