HL 60 leukaemia cells chemically induced to differentiate retain some surface glycan features of undifferentiated cells not found in normal leukocytes.

International audienceHuman HL 60 myeloid leukaemia cells have the potential to differentiate into either macrophage-like cells or granulocyte-like cells under the stimulus of chemical treatments. Using glycotechnology procedures, the glycosylation patterns of differentiated and undifferentiated HL 60 cells were analysed and compared with those of normal human peripheral monocytes. Both in vitro differentiations result in significant morphologic and functional changes, but we observed that the glycosylation patterns of undifferentiated and differentiated HL 60 cells exhibit several common glycosidic features that are absent in normal peripheral monocytes: the presence of (i) bisecting beta-N-acetylglucosamine attached at the C-4 position of the beta-mannose of polyantennary complex-type carbohydrate chains and (ii) complex-type carbohydrate chains enriched with non-reducing terminal beta-N-acetylglucosamine residues. Moreover, the three populations of HL 60 cells express small amounts of biantennary complex-type structures ( 20% of such structures. Thus, the cell glycosylation pattern could reflect the pathological state of the HL 60 cells

Phorbol ester treatment of HL 60 leukemia cells results in increase of beta-(1 --> 4)-galactosyltransferase.

International audienceWe previously showed that HL 60 leukemia cells exhibit various changes in their cellular glycans after phorbol 12-myristate 13-acetate (PMA) treatment. These changes could originate largely from changes in one or several glycosyltransferases. In this report, we show using enzymatic measures, fluorescence microscopy, immunoblotting and Northern blot that beta-(1 --> 4)-galactosyltransferase I (GalT I) activity was higher (> x 2) in PMA-treated compared with untreated HL 60 cells. Immunoblotting showed an increased intensity of the GalT I band at 49 kDa and Northern blot a weak increase of the GalT I transcript band, after PMA treatment. Moreover, Northern blot performed after actinomycin-D treatment of the cells, which inhibits transcription, suggests that the observed increase of GalT I expression could originate, in part, from increase of the stability of GalT I transcripts

T lymphocyte activation results in an increased expression of beta-1,4-galactosyltransferase: phorbol ester induces a similar enhancement in the absence of mitosis.

International audienceWe previously showed that in vitro activated human T lymphocytes expressed increased amounts of beta-1,6-branched N-linked oligosaccharides (Lemaire S etal. (1994) J Biol Chem269: 8069-74), which have been proposed to participate in the regulation of the immune process. In the present paper, we compared the activity and expression of beta-1,4-galactosyltransferase (GalT), one of the glycosyltransferases involved in the biosynthesis of these beta-1,6-branched N-linked oligosaccharides, before and after in vitro activation of T lymphocytes after a 40h treatment with a mixture of phorbol 12-myristate 13-acetate and Phaseolus vulgaris lectin. After treatment, the enzymatic activity of the GalT was significantly increased and immunoblot experiments performed with a monoclonal antibody to human GalT showed an increased intensity of the GalT band at 49 kDa, attributable to an enhancement of GalT mRNA level, as shown by Northern blots. However, treatment of the same T-lymphocytes by phorbol ester alone, which is unable to induce mitosis, resulted in a comparable increase of the expression of GalT. Moreover, these phorbol ester-treated T lymphocytes, analysed by flow cytometry exhibited a two-fold increase in the expression of GalT. Finally, confocal fluorescence microscopy performed on all T lymphocytes (treated or not) showed that the flow cytometric signal of GalT originates from intracellular, Golgi-associated antigen only since no surface GalT was detected

Circulating malignant lymphocytes from Sezary syndrome express high level of glycoproteins carrying beta (1-6)N-acetylglucosamine-branched N-linked oligosaccharides.

International audienceThe circulating forms of malignant cells from patients with Sezary syndrome exhibit on their glycoproteins a high level of beta (1-6)GlcNAc-branched N-linked oligosaccharides, a particular species of glycans related to the metastatic potential of several tumors and T lymphocytes activation. An increased activity of the N-acetylglucosaminyltransferase V and of the beta (1-4)galactosyltransferase, two enzymes implicated in beta (1-6)GlcNAc-branching is also found. Nevertheless, contrary to activated normal T lymphocytes, Sezary lymphocytes in agreement with their non-proliferating state, do not exhibit increased thymidine uptake. This result suggests that expression of the beta (1-6)GlcNAc-branched N-linked carbohydrates could be related to some of the malignant properties of Sezary lymphocytes