chondroitin-sulfates and Leukemia--Myeloid

A clone of natural killer (NK) cells (JTB18) was found to be ultrastructurally similar to peripheral blood large granular lymphocytes (LGL). These cells incorporated [35S]sulfate into cell-associated proteoglycan molecules, which were then isolated by CsCl density gradient centrifugation. As assessed by gel filtration chromatography, the native 35S-labeled proteoglycan and its beta-eliminated 35S-labeled glycosaminoglycans were of Mr approximately 200,000 and 50,000, respectively. The 35S-labeled proteoglycans were resistant to proteolysis, since their Mr were apparently not altered by incubation with either pronase or S. aureus V8 protease. The purified NK cell 35S-labeled proteoglycans were degraded by approximately 90% to 35S-labeled disaccharides with either chondroitinase ABC or AC. High performance liquid chromatographic analysis of the digests revealed these disaccharides to be composed entirely of chondroitin sulfate A (glucuronic acid----N-acetylgalactosamine-4SO4). Whole 35S-labeled cells incubated with chondroitinase ABC failed to release 35S-labeled disaccharides into the supernatant, and x-ray energy-dispersive analysis revealed that sulfur-containing molecules were present in the intracellular granules, thereby localizing the NK cell-associated proteoglycan primarily in the granules of the cell, rather than on the plasma membrane. The 35S-labeled cloned NK cells incubated for 30 min to 4 h with K562 tumor cell targets at a 0.5:1 ratio exocytosed a mean of 49% of the granular 35S-labeled proteoglycans during the first 60 min of the culture. Proteoglycan release was maximal with an effector/target cell ratio of 0.5:1 for JTB18:K562. Significant proteoglycan release from JTB18 NK cells was also obtained with other sensitive target cells such as REX, Molt4, and CEM, but not with cells such as KG1 and Laz156, which have been shown previously to be resistant to killing by this NK cell. Thus, protease-resistant intracellular proteoglycans with chondroitin sulfate A side chains are specifically exocytosed from the granules of human NK effector cells upon contact with sensitive targets, suggesting that these proteoglycans may be involved in the mechanism of cytotoxicity.

Topics: Cell Line; Chondroitin; Chondroitin Sulfates; Clone Cells; Cytoplasmic Granules; Cytotoxicity, Immunologic; Exocytosis; Humans; Killer Cells, Natural; Leukemia, Myeloid; Leukemia, Myeloid, Acute; Macromolecular Substances; Microscopy, Electron

The average glycosaminoglycan content in control spleens, expressed as uronic acid, was 0.23 +/- 0.02 mg/g of dry wt; the average glycosaminoglycans content in spleens of CML patients, expressed as uronic acid, was 0.91 +/- 0.23 mg/g of dry wt. In control and in leukemic spleens the same glycosaminoglycans were present, that is hyaluronic acid, heparan sulphate, dermatan sulphate, chondroitin-4-sulphate and chondroitin-6-sulphate. However, in leukemic spleens the normal quantitative relationship between these glycosaminoglycans was greatly modified; in fact in control spleens hyaluronic acid, heparan sulphate and the chondroitin sulphates were present in almost equal proportions, whereas in leukemic spleens the chondroitin sulphate group alone represented almost 9/10 of all the glycosaminoglycans. Since this proportion is weakly modified in leukemic spleens in which the number of myeloid cells has been notably reduced after chemotherapy, we may suppose that this phenomenon is due to the very marked modifications which take place in the micro-environment of the leukemic spleen.

Topics: Chondroitin Sulfates; Dermatan Sulfate; Electrophoresis, Cellulose Acetate; Glycosaminoglycans; Heparitin Sulfate; Humans; Hyaluronic Acid; Leukemia, Myeloid; Spleen