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The Chédiak-Higashi syndrome: ring-shaped lysomomes in circulating monocytes
Insights
Giant inclusion anomaly in Chédiak-Higashi syndrome (CHS) leukocytes, particularly monocytes, presents as unique ring-shaped organelles. These structures, containing lysosomal enzymes, challenge previous understandings of CHS granule formation.
Area of Science:
- Cell Biology
- Hematology
- Genetics
Background:
- Chédiak-Higashi syndrome (CHS) is characterized by giant inclusion anomalies in leukocytes.
- Previous studies suggested a uniform giant granule formation across all CHS leukocyte types.
Purpose of the Study:
- To reexamine the ultrastructural and cytochemical features of leukocyte giant inclusions in CHS patients.
- To clarify the specific nature and origin of giant granules in CHS monocytes.
Main Methods:
- Ultrastructural analysis of leukocytes from three CHS patients.
- Cytochemical staining for peroxidase and acid phosphatase.
- Emphasis on monocyte morphology and granule composition.
Main Results:
- CHS monocytes exhibit ring-shaped organelles as the primary disease manifestation, not uniform giant granules.
- These ring-shaped organelles possess a double membrane enclosing cytoplasm and azurophilic granules.
- Peroxidase and acid phosphatase activity localized between the double membranes indicate lysosomal identity.
- Similar, though infrequent, double-ring structures were observed in neutrophils, eosinophils, and lymphocytes.
Conclusions:
- CHS monocytes display unique ring-shaped organelles, distinct from previously assumed uniform giant granules.
- These organelles are derived from or share common origins with primary lysosomes.
- The findings refine the understanding of cellular pathology in Chédiak-Higashi syndrome.
Abstract:
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.