Ultrastructural Identification of Acid Complex Carbohydrate in Cytoplasmic Granules of Normal and Leukaemic Human Monocytes

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Abstract
Complex carbohydrate in granules of monocytes was compared with that in granules of neutrophils by ultrastructural cytochemical methods. The acid mucosubstance in granules of both cell types stained with dialyzed Fe after brief fixation with dilute glutaraldehyde, but that in monocyte granules differed in failing to stain after stronger fixation. Approximately 10% of granules in normal blood monocytes stained with this method, whereas more than 90% of granules in leukemic monocytes from 2 of 7 patients with acute myelomonocytic leukemia stained intensely. This difference presumably results from unmasking of acid groups in immature granules or increased synthesis of granule mucosubstance in some leukemic monocytes. Granules of monocytes differed further from those of neutrophils in failing after either type of fixation to stain with a high Fe diamine technique for demonstration of sulfated mucosubstance. The absence of high Fe diamine staining could reflect a lack of sulfate esters in monocyte granule mucosubstance, masking of the sulfate groups by other components or extraction of the sulfated mucosubstance during specimen processing.