The Chédiak-Higashi syndrome: ring-shaped lysomomes in circulating monocytes.

The giant inclusion anomaly of leukocytes from three patients with the Chédiak-Higashi syndrome (CHS) has been reexamined by the ultrastructural and cytochemical techniques placing emphasis on the monocyte. Contrary to previous assumptions that all CHS leukocytes shared a common form of giant granule with similar mechanisms of formation, it is shown that CHS monocytes contain ring-shaped organelles as their principle manifestation of the disease. These granules consist of a double membrane surrounding a segment of cytoplasm, which may or may not be sequestered from the remaining cytoplasm and which usually contains one or more normal-sized azurophilic granules. The material lying between the double membranes contains the specific reaction products for peroxidase and acid phosphatase. Therefore, the ring-shaped organelles share identity with the azurophilic granules and probably share a common origin with the primary lysosomes. The double-ring form of giant CHS organelle has also been found infrequently in neutrophils, eosinophils, and lymphocytes.