Characterization of glycosaminoglycans in human leukocytes: enzymatic subunit assay of isomeric chondroitin sulfates

Distinct patterns of sulfated proteoglycan biosynthesis in human monocytes, granulocytes and myeloid leukemic cells

The production of sulfated proteoglycans was compared in mature peripheral blood granulocytes and monocytes and HL-60 promyelocytic leukemia cells. We found that HL-60 cells synthesized 5-10 times more proteoglycans than peripheral blood leukocytes. Differentiation of HL-60 cells toward mature monocytes by treatment with 12-O-tetradecanoyl-phorbol-13-acetate (TPA) or towards granulocytes by treatment with retinoic acid or dibutyryl cyclic adenosine-3',5'-monophosphate (dbcAMP) resulted in a small (20-30%) decrease in sulfated proteoglycan biosynthesis. Chondroitin sulfate was found to be the predominant proteoglycan produced by monocytes, PMN and undifferentiated HL-60 cells. Differentiated HL-60 cells produced chondroitin sulfate as well as sulfated proteoglycans sensitive to nitrous acid degradation. Similar results were observed in TPA, dbcAMP and retinoic acid differentiated HL-60 cells indicating that the changes in proteoglycan biosynthesis observed were independent of the developmental pathway. Using specific monoclonal antibodies and flow cytometry, we also found that HL-60 cells and monocytes produced chondroitin-4-sulfate, chondroitin-6-sulfate and chondroitin-O-sulfate while PMN only produced chondroitin-4-sulfate. In addition, although there were no significant differences in antibody binding to undifferentiated and differentiated HL-60 cells, the tumor cells bound 5-20 times more of the antibodies than the peripheral blood leukocytes. Our data demonstrate that sulfated proteoglycan production by HL-60 cells is distinct from PMN and monocytes. In addition, the fact that differentiated HL-60 cells continue to synthesize larger amounts of the proteoglycans than the peripheral blood leukocytes indicates these cells have not completely matured.

Mucosubstances of rabbit granulocytes studied by means of electron-microscopic radioautography and X-ray microanalysis

Rabbit bone marrow cells have been studied by means of light- and electron-microscopic radioautography and X-ray microanalysis. Carrier free sulfuric acid was used as the radioactive precursor in this experiment. Immature granulocytes showed more active incorporation than mature ones. Silver grains were observed in the Golgi apparatus and granules in three kinds of granulocytes. Electron-microscopically, immature granules showed the incorporation of inorganic sulfate, while mature ones did not. Sulfur was detected in all kinds of granules of the three granulocyte types by X-ray microanalysis. It is concluded that incorporated inorganic sulfur may be utilized for the synthesis of acid glycosaminoglycans and the sulfur detected by X-ray microanalysis may be that contained in the acid glycosaminoglycan. The sulfur detected in the specific granules of the heterophil probably derives from proteins or polypeptides incorporating sulfur containing amino acids.

The influence of the type of sulphate bond and degree of sulphation of glycosaminoglycans on their interaction with lysosomal enzymes

Significant differences occur between the interaction of several sulphated glycosaminoglycans with a particular lysosomal protein, leading to inhibition in the case of lysosomal enzymes. The order of strength of inhibition at pH4 was: heparin greater than chondroitin 4-sulphate = chondroitin 6-sulphate greater than dermatan sulphate.

Ultrastructural identification of acid complex carbohydrate in cytoplasmic granules of normal and leukaemic human monocytes

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 dialysed iron after brief fixation with dilute glutaraldehyde, but that in monocyte granules differed in failing to stain after stronger fixation. Approximately 10% granules in normal blood monocytes stained with this method, whereas more than 90% of granules in leukaemic monocytes from two of seven patients with acute myelomonocytic leukaemia stained intensely. This difference presumably results from unmasking of acid groups in immature granules or increased synthesis of granule mucosubstance in some leukaemic monocytes. Granules of monocytes differed further from those of neutrophils in failing after either type of fixation to stain with a high iron diamine technique for for demonstration of sulphated mucosubstance. The absence of high iron diamine staining could reflect a lack of sulphate esters in monocyte granule mucosubstance, masking of the sulphate groups by other components, or extraction of the sulphated mucosubstance during specimen processing.

Cellular glycosaminoglycans in lymphocytes from patients with cystic fibrosis

Cellular glycosaminoglycans were isolated from lymphocytes from patients with cystic fibrosis and controls. The isolated glycosaminoglycans were fractionated by cellulose acetate electrophoresis, analyzed for glucosamine and galactosamine content, and subjected to hydrolysis with bovine testicular hyaluronidase. The total glycosaminoglycan content, the per cent glucosamine and galactosamine, and the distribution of cellular glycosaminoglycans in circulating lymphocytes in cystic fibrosis were no different from controls.