Ultrastructural morphology, cytochemistry, and morphometry of eosinophil granules in Chédiak-Higashi syndrome.

Lysosomal enlargement in Chédiak-Higashi Syndrome (CHS) occurs to varying degrees in different cell types and has provided insight into the pathophysiology of lysosomal granules. This study was undertaken to determine the extent of involvement of eosinophil crystalloid granules (CGs) and smaller non-crystalloid granules (NCGs) in giant granule formation. Eosinophils from two CHS patients were evaluated after glutaraldehyde fixation and staining for morphologic examination, peroxidase, and complex carbohydrate using uranyl acetate-lead citrate, diaminobenzidine-lead citrate, and periodate-thiocarbohydrazide-silver proteinate (PA-TCH-SP) methods, respectively. Although many CGs appeared normal in shape and size, several CGs appeared enlarged and a few measured over 5 microns in diameter, consistent with giant granule formation in CHS. These giant granules either occasionally contained a single large crystalloid or, more frequently, contained numerous normal-size crystalloids. Enlargement of granules was also observed in some precursor CGs of bone marrow early eosinophils, indicating that giant granule formation was initiated during granule genesis. Almost all NCGs in late eosinophils were small granules and stained strongly with PA-TCH-SP in contrast to CGs. Most, but not all small granules were peroxidase-positive in eosinophil precursors, whereas the percentage of peroxidase-negative small granules increased in late eosinophils. This indicated the presence of at least two small granule populations. Morphometric studies indicated CHS selectively involved CGs and demonstrated that neither the average size nor numbers of NCGs were significantly different from normal eosinophils. Thus, these studies indicate that CHS selectively involves CGs, and demonstrate preservation of normal granule size and heterogeneity for NCGs in late eosinophils. These observations suggest that the underlying CHS pathophysiology does not involve all lysosomal subpopulations.