Leukemic leukocytes from 12 patients with acute myelogenous leukemia (AML) and two patients with chronic myelogenous leukemia (CML) were isolated by centrifugations in Percoll gradients, and examined for total carbohydrates. In leukemic leukocytes from 10 of these patients ceramide-bound carbohydrates were also determined. Protein-bound carbohydrates were calculated by subtraction of ceramide-bound carbohydrates from total carbohydrates. In all samples analysed the contents of total and protein-bound carbohydrates were much lower in leukemic leukocytes than in normal neutrophils, irrespective whether the results were expressed relative to protein, DNA, cell number or dry mass. For immature leukemic cells of MO-M1 phenotype differences up to 10-fold were observed. Contents of ceramide-bound carbohydrates, i.e. those of neutral and acidic glycosphingolipids (GSLs) were also low in leukemic cells. However, when GSL carbohydrates were calculated as percentage of total carbohydrates, GSLs in leukemic leukocytes were elevated in half of the AML patients but depressed in the other half. The results are discussed in the light of the hypothesis on GSL function by one of us (Kościelak J., 1986, Glycoconjugate J. 3, 95-108). According to one element of the hypothesis, during cell differentiation newly synthesized glycoproteins (GPs) that perform specific functions are added to house-keeping GPs that are present in plasma membranes of all types of cells. Thus, during differentiation, the GP content of the cell membrane should increase and that of the so called "membrane packing" glycosphingolipids should decrease.
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