Heterogeneity of peroxidase-positive granules in normal human an Chédiak-Higashi neutrophils

Abstract

Studies have demonstrated significant heterogeneity in neutrophil granule morphology and physical density. This study evaluated the heterogeneity morphometrically, morphologically, cytochemically, and biochemically. Intact human peripheral blood neutrophils collected from normal volunteers and a patient with Chédiak-Higashi syndrome (CHS) and isolated normal neutrophil granules were processed for ultrastructural morphology and peroxidase staining. Intact cells, nuclei, and granule profiles were analyzed by computer-assisted planimetry. Peroxidase-positive granules (PPG) represented about 40% of normal neutrophil granules and covered the entire spectrum of granule size. PPG in the least-dense fractions of isolated granules were significantly smaller than in higher-density fractions. PPG in low- and intermediate-density fractions differed from high-density fraction by moderate to strong vicinal glycol staining with Thiéry's periodate-thiocarbohydrazide-silver proteinate method. Differing ratios of % beta-glucuronidase/% myeloperoxidase (MPO) across granule fractions indicated PPG heterogeneity. Morphometric analysis of neutrophils treated with 1 microM calcium ionophore A23187 did not show significant differences in PPG size or number. Biochemically analyzed MPO in these cells was preserved, although the number of peroxidase-negative granules (PNG) and levels of vitamin B12-binding protein were markedly decreased. In CHS, about 20% of granules were PPG. Analysis of CHS neutrophils revealed the persistence of microgranules similar to normals. PNG number and volume fractions of PPG and TG were not different from normals. Complex heterogeneity of normal PPG was quantitated using morphometry and appeared preserved in ionophore-treated cells but was uniquely modified in CHS.