engleski

Electron-microscopic study of the Chediak-Higashi syndrome

The Chediak-Higashi syndrome (CHS) is associated with giant neutrophil granules. A similar granular abnormality is seen in granulopoietic cells in the marrow and in eosinophils, monocytes and lymphocytes. The inheritance is autosomal recessive. Affected children usually have neutropenia and thrombocytopenia, and suffer from recurrent severe infections. Clinical examination frequently reveals partial albinism, photophobia, nystagmus and intermittent febrile episodes. Some patients developed hepatosplenomegaly, lymphadenopathy and widespread organ infiltrates with mononucleated cell during the "accelerated (lymphoma like) phase". The majority die in childhood from infection or haemorrhage. A 16-year-old female was admitted to the Clinical Hospital "Merkur" in April, 1992. For four months, the patient had several febrile episodes of unknown cause. On admission, physical examination revealed fever, partial albinism, silvery gray tinted hair, photophobia, moderate hepatosplenomegaly and lymphadenopathy. Abnormal laboratory findings included neutropenia with lymphocytosis, thrombocytopenia and typical large cytoplasmic inclusions in peripheral blood and bone marrow leukocytes, morphologically and cytochemistrally diagnostic of CHS. Samples from bone marrow aspirates were fixed for electron-microscopic examination by immersion in 2% glutaraldehyde and 2% paraformaldehyde in phosphate buffer. After 3 hours fixation specimens were postfixed for 1 hour in 1 % osmium tetroxide and dehydrated in ascending concentrations of ethanol. The specimens were embedded in Durcopan (Fluka). Ultrathin sections were examined with electron microscope Zeiss 902A. Electron-microscopic examination of bone marrow revealed the presence of large granules in the lymphocytes, neutrophil and eosinophils. The giant lysosome-like organelles of various sizes showed electron-microscopic morphologic sirnilarities to abnormal primary (azurophilic, nonspecific) granules. They are spherical or elliptical in shape and are surrounded by a unit membrane. Commonly, the contained dense spherical structures, mostly along the surrounding membrane of the organelle. The hypothesis that the abnormal giant leukocyte granules are lysosomal includes: electronmicroscopic morphology, the presence of acid phosphatase activity as a lysosomal marker within the granules and the presence of myeloperoxidase activity in them. Additionally, it is known that the giant lysosomes of CHS are also functionally abnormal.

Electron-microscopic study ; Chediak-Higashi syndrome

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