The glycosphingolipid globoside as a serological marker on cytolytic T lymphocyte precursors and alloantigen-responsive proliferating T lymphocytes in murine spleen

Establishment of cells exhibiting mutated glycolipid synthesis from mouse thymus by immortalization with SV-40 virus

Immortalization with simian virus-40 and cloning of immortalized cells from mouse thymus were performed to establish cell lines for characterization of the mode of glycolipid expression in the thymic cells. Among the 25 cell lines obtained, three lines with different morphologies were established, that is, epithelial (IMTH-E), fibroblastic (IMTH-F), and asterisk-like (IMTH-I) cells, and their glycolipids, together with those in the thymus, were determined systematically. The major glycolipids in mouse thymus were the globo- and ganglio-series, both of which, were co-expressed in the three cell lines established. However, the mode of modification of the globo- and ganglio-series was distinct for each cell line. As to the globo-series, the structures with the longest carbohydrate chain for IMTH-E, -F, and -I cells were Gb3Cer, Gb4Cer, and Forssman antigen, respectively, having stepwise shorter carbohydrates at the nonreducing termini. Although the acidic glycolipids in IMTH-E cells comprised GM3 and GM2, and their sulfated isomers, IMTH-F and -I cells expressed GMlb and GDlc for the alpha-pathway, and up to GDI a for the a-pathway of ganglio-series glycolipids. GMlb-GalNAc present in the thymus was not detected in IMTH-F and -I cells, probably due to the lower synthetic activity for the metabolic intermediate Gg4Cer. The results indicate that the immortalization technique is useful for obtaining individual cells having unique glycolipid profiles for analysis of the functional significance and metabolism of glycolipids in the thymus.

Changes in the glycolipid composition and characteristic activation of GM3 synthase in the thymus of mouse after administration of dexamethasone

Glycolipids in the thymus of mice after administration of dexamethasone were compared with those in control mice. In parallel with a decrease in the tissue weight due to the disappearance of immature thymocytes in the cortex, the amounts of GlcCer, Gg4Cer and GM1 decreased from 18 h after intraperitoneal administration of dexamethasone, but those of Gb4Cer and Forssman glycolipid did not change, indicating the differential distribution of ganglio- and globo-series glycolipids in the thymus, GlcCer, Gg4Cer and GM1 being on dexamethasone-sensitive cortical thymocytes, and Gb4Cer and Forssman glycolipid on dexamethasone-resistant cells including thymic stromal cells, respectively. At the same time, a characteristic increase in GM3, whose amount per thymus and concentration per mg of thymus were increased 4-fold and 13-fold compared to those in the control mice, respectively, was observed at the onset of the decrease in tissue weight and was due to the increased activity of LacCer sialyltransferase with the enhanced expression of its gene and the concomitant decrease in cytosolic sialidase activity. One can suggest that endogenous accumulation of GM3 is involved in the dexamethasone-induced apoptosis of cortical thymocytes. On radiolabeling of the thymus with CMP-[14C]-NeuAc, the incorporation of radioactivity into GM3 was preferentially observed in the thymuses of dexamethasone-administered mice, but not in those of control mice, suggesting the possible involvement of plasma membrane-associated sialytransferase in GM3 synthesis in the thymuses of dexamethasone-administered mice.

Expression of glycosphingolipids in lymph nodes of mice lacking TNF receptor 1: biochemical and flow cytometry analysis

The expression of gangliosides and neutral glycosphingolipids (GSLs) in the lymph nodes of mice lacking the gene for the tumour necrosis factor-alpha receptor p55 (TNFR1) has been investigated. GSL expression in the tissues of mice homozygous (TNFR1-/-) or heterozygous (TNFR1+/-) for the gene deletion was analysed by flow cytometry and high-performance thin-layer chromatography (HPTLC) followed by immunostaining with specific antibodies. HPTLC immunostaining revealed that lymph nodes from TNFR1-/- mice had reduced expression of ganglioside GM1b and GalNAc-GM1b, neolacto-series gangliosides, as well as the globo- (Gb3, Gb4 and Gb5) and ganglio-series (Gg3 and Gg4) neutral GSLs. Flow cytometry of freshly isolated lymph node cells showed no significant differences in GSL expression, except for the GalNAc-GM1b ganglioside, which was less abundant on T lymphocytes from TNFR1-/- lymph nodes. In TNFR1-/- mice, GalNAc-GM1b+/CD4+ T cells were twofold less abundant (3.8% vs 7.6% in the control mice), whereas GalNAc-GM1b+/CD8+ T cells were fourfold less abundant (5.0% vs 20.2% in the control mice). This study provides in vivo evidence that TNF signalling via the TNFR1 is important for the activation of GM1b-type ganglioside biosynthetic pathway in CD8 T lymphocytes, suggesting its possible role in the effector T lymphocyte function.

Immunohistological and flow cytometric analysis of glycosphingolipid expression in mouse lymphoid tissues

Expression of neutral glycosphingolipids (GSLs) and gangliosides in normal lymphoid tissues and cells has been studied mostly by biochemical and immunochemical analysis of lipid extracts separated by thin-layer chromatography. GSLs and gangliosides involved in the GM1b biosynthetic pathway were assigned to T-lymphocytes, whereas B-cell gangliosides and GSLs have been poorly characterized in former publications. We used specific polyclonal antibodies in immunohistochemistry and flow cytometry to analyze the distribution of globotriaosylceramide (Gb(3)Cer), globoside (Gb(4)Cer), gangliotriaosylceramide (Gg(3)Cer), gangliotetraosylceramide (Gg(4)Cer), and gangliosides GM3 and GalNAc-GM1b in the mouse thymus, spleen, and lymph node. Immature thymocytes expressed epitopes recognized by all antibodies, except for anti-Gb(4)Cer. Mature thymocytes bound only antibodies to GalNAc-GM1b, Gg(4)Cer, and Gb(4)Cer. In secondary lymphoid organs, antibodies to globo-series GSLs bound to vascular spaces of secondary lymphoid organs, whereas the ganglio-series GSL antibodies recognized lymphocyte-containing regions. In a Western blotting analysis, only GalNAc-GM1b antibody recognized a specific protein band in all three organs. Flow cytometric analysis of spleen and lymph node cells revealed that B-cells carried epitopes recognized by all antibodies, whereas the T-cell GSL repertoire was mostly oriented to ganglio-series-neutral GSLs and GM1b-type gangliosides. The results of immunohistochemistry and flow cytometry were not always identical, possibly because of crossreactivity to glycoprotein-linked oligosaccharides and/or differences between cell surface carbohydrate profiles of isolated cells and cells in a tissue environment.

Cyclic AMP causes differentiation and decreases the expression of neutral glycosphingolipids in cell cultures derived from a malignant glioma

Cultures derived from a malignant glioma (U-87 MG) were treated with 3 mM dibutyryl cAMP. The treatment resulted in morphological differentiation of the cultures and a decrease in cell proliferation. Biochemically, dibutyryl cAMP treatment caused a general reduction in the concentration of neutral glycosphingolipids in the U-87 MG cells. The concentration of individual neutral glycosphingolipids in the untreated cells was 1.8- to 3.0-fold higher than in cells treated for 72 h with 3 mM dibutyryl cAMP. Cells were labeled with [3H]galactose to monitor synthesis of the neutral glycosphingolipids. Decreased synthesis was noted in cells treated with dibutyryl cAMP as compared with untreated cells as indicated by decreased uptake of [3H]galactose label. The ganglioside composition of the cells was essentially unchanged after dibutyryl cAMP treatment.

Concanavalin A-stimulated expression of gangliosides with GalNAc beta 1-4(NeuAc alpha 2-3)Gal beta structure in murine thymocytes

We analysed the glycolipids of mouse thymocytes before and after Concanavalin A (Con A) or recombinant interleukin-2 (rIL-2) stimulation by TLC-immunostaining with carbohydrate-specific antiglycolipid antibodies. The thymocytes were cultured in serum-free medium in the presence of 500 ng ml-1 Con A, 10 U ml-1 rIL-2 or Con A plus rIL-2 for 6, 12, 24, 48, and 72 h, and were found to start proliferating 24 h after cultivation in the presence of Con A or Con A plus rIL-2, the maximum levels being reached at 72 h and 48 h, respectively, in a thymidine uptake experiment. The concentrations of II3Neu-Gg4Cer, Gg4Cer and IV3GalNAc alpha-Gb4Cer after 48 h Con A stimulation were found to be at almost the original levels. Conversely, II3Neu-Gg3Cer, which was not detected in the thymocytes at the start, began to appear after 48 h stimulation with Con A and Con A plus rIL-2, and IV3Neu-Gg5Cer in the cells 48 h after stimulation with Con A and Con A plus rIL-2 has increased to 41 and 44 times higher than in the original cells, respectively, as judged on TLC-immunostaining with monoclonal antibody YHD-06, which detects the GalNAc beta 1-4(NeuAc or NeuGc alpha 2-3)Gal beta-structure. These results indicate that the increased synthesis of both gangliosides, in other words, the activation of N-acetylgalactosaminyltransferase, is associated with the mitogen-induced proliferation.(ABSTRACT TRUNCATED AT 250 WORDS)

Preferential reactivity of autoantibodies in murine lupus NZB mice to neuraminidase-treated monosialogangliosides on B cells of mouse spleen

When analyzed by flow cytometry, reactivity of IgM autoantibodies in sera from NZB mice to spleen B cells, but not to T cells, from BALB/c mice was remarkably increased after treatment of the cells with Vibrio cholerae neuraminidase. By TLC immunostaining with the antibodies, neither neutral nor acidic glycosphingolipids from both BALB/c and NZB mouse spleens were found to be reactive, but after neuraminidase treatment of the TLC plate, prior to the immunostaining, three components became reactive. All of the reactive glycosphingolipids were found to carry a single sialic acid residue and were at a concentration less than 1.3% of the total lipid-bound sialic acids. Their mobilities on TLC plate were close to those of IV3 NeuAcnLc4Cer, IV3 NeuAcII3 NeuAcGg4Cer, and IV3 NeuAcII3 NeuAc2Gg4Cer. In addition, the monosialogangliosides, which became reactive with the autoantibodies after neuraminidase treatment, were found to be predominantly distributed on B cells from BALB/c mice spleen, but not on T cells by TLC immunostaining. These studies demonstrate that the majority of IgM autoantibodies to spleen lymphocytes in sera from NZB mice might react preferentially to terminal sugar residues of three new glycosphingolipids masked by a single sialic acid on B cells, but not on T cells.

Immunohistochemical localization of Forssman glycosphingolipid-positive macrophages and reticular cells in murine lymphoid tissue

Forssman (Fo) glycolipid antigen, as detected by a monoclonal antibody (mAb), is expressed by a subpopulation of murine macrophages in the spleen and peripheral lymph nodes. The histological distribution of Fo antigen in spleen and lymph nodes was studied by immunostaining of cryosections, and was compared with the staining pattern of four other mAbs known to recognize macrophage subpopulations: F4/80, Mac-1, MOMA-1, and ERTR-9. Fo+ macrophages were found exclusively in the red pulp of the spleen and the medulla of inguinal and axial lymph nodes. Macrophages in the other lymphoid organs were Fo-. Besides macrophages, reticular cells in T-dependent areas of spleen and lymph nodes were Fo+. Attempts to grow colonies of Fo+ macrophages from either bone marrow or spleen precursors were negative. While the usual number of F4/80+ colonies was obtained, only a few, small clusters of Fo+ macrophages were formed, which speaks against an early commitment of precursors to express Fo.

Glycosphingolipids in lectin-resistant variants of mouse Lewis lung carcinoma cells

Neutral glycolipids and gangliosides from murine Lewis lung carcinoma cell line LL2 and its lectin-resistant variants, differing in metastatic properties, were studied by fast-atom-bombardment mass spectrometry (FAB-MS), exoglycosidase treatment and an immunostaining procedure. The neutral glycolipids identified in all cell lines studied included CMH, CDH, CTH, asialo GM2, globoside and a glycolipid with a preliminary structure of Hex-Hexl-4HexNAc-Hex-Hex-Cer. The major gangliosides were GM3, GM2, GM1 and GD1a. No qualitative differences in glycosphingolipid expression were found between the metastatic cell lines (LL2 and LL2AAA) and the weakly metastatic variants (LL25, LL28, LL230 and LL2RCA II). Some quantitative differences were observed between the cell lines, e.g., in the level of ganglioside-bound sialic acid, which was not apparently correlated with the metastatic capacities.

Glycosphingolipids of human urothelial cell lines with different grades of transformation

Neutral glycolipids and gangliosides from seven human urothelial cell lines, differing in grades of transformation (TGr), were characterized by fast atom bombardment mass spectrometry, exoglycosidase treatment and an immunostaining procedure. The major neutral glycolipids identified in all cell lines studied included CMH, CDH, CTH, globoside and paragloboside, the gangliosides were GM3, GM2, sialosylparagloboside and GD1a. The following observations were made: 1. GM2 was the major ganglioside in the TGrII cell lines (non-tumorigenic, non-invasive), but a minor component in the TGrIII cell lines (tumorigenic, invasive). 2. All components showed C16:0 and C24:0 as major fatty acids, but in the TGrIII cell lines the fatty acid composition of CMH and some of the gangliosides were more complex showing unsaturated and hydroxy-fatty acids as well.

Heparin inhibits specific glycosyltransferase activities in interleukin 2 activated murine T cells

In order to better understand the role of cell surface glycolipids in T lymphocyte activation, heparin was used to simultaneously modulate the expression of glycolipids and the lytic capacity of lymphocytes activated by interleukin-2. Results presented here show that heparin added at the start of a 3 day culture inhibited the formation of lymphokine activated killer cells by up to 50%. Heparin also has a profound effect on the synthesis of glycolipids during this three day period. Asialo GM1, a useful cell surface marker for subsets of murine cytotoxic cells, is reduced in amount, as are the other two major neutral glycolipids lactosylceramide and asialo GM2. In addition, the synthesis of some gangliosides is affected by heparin treatment. Comparison of the glycosyltransferase activities of untreated and heparin-treated cells shows that the activities of a 2-3-sialyltransferase and a beta 1-3 galactosyltransferase are inhibited dramatically, while a third enzyme, N-acetyl-galactosaminyltransferase is unaffected. The two heparin inhibitable enzymes bind to heparin affinity columns but the galactosaminyltransferase does not. These studies suggest that the proper regulation of the activities of specific glycosyltransferases may be important events in lymphocyte activation.

Structural characterization of gangliosides from murine T lymphocytes

Mouse spleen cells were prepared from CBA/J mice, and T lymphocytes were selectively stimulated with the T cell mitogen concanavalin A and further propagated in the presence of the T cell growth factor interleukin-2. The T cells were metabolically labeled with D-[1-14C]galactose and D[1-14C]glucosamine, and the gangliosides were extracted and purified by DEAE-Sepharose column chromatography. Carbohydrate backbone structures of the asialogangliosides, prepared by mild acid hydrolysis, were determined by high-performance liquid chromatography, treatment with exoglycosidases and immunostaining. Monosialylated gangliosides were isolated by gradient elution from DEAE-Sepharose and further separated by preparative high-performance thin-layer chromatography in two solvent systems. Isolated fractions were characterized by preparation of asialogangliosides by mild acid hydrolysis, the action of Vibrio cholerae neuraminidase, and fast-atombombardment mass spectrometry. The following structures were identified: IVNeuAc-GgOse4Cer; IVNeuGc-GgOse4Cer; IVNeuAc-GgOse5Cer; and IVNeu-Gc-GgOse5Cer. The latter two gangliosides were not detected on B lymphoblasts and may be T-cell-specific structures. All gangliosides were heterogeneous in their ceramide moieties, being substituted with C16:0, C24:0, and C24:1 fatty acids. A preliminary study of several other mouse strains showed no strain-specific genetic variations in the T cell gangliosides. The possible role of these gangliosides is discussed.

Glycosphingolipids of the globo-series are associated with the monocytic lineage of human myeloid cells

Neutral glycosphingolipids (neutral GSLs) of the human myeloid leukemia cell lines ML-2, ML-3, HL-60 and THP-1-0 were metabolically labeled with [3H]galactose and [3H]glucosamine, and analyzed by high-performance liquid chromatography. They were compared with unlabeled neutral GSLs from purified human granulocytes and monocytes. Neutral GSLs were identified by retention times and the structures were further confirmed by degradation with specific exoglycosidases. Two neutral GSLs of the globoseries, globotetraosylceramide and globotriaosylceramide were found in monocytes and the monoblastic leukemia line THP-1-0. The leukemia-derived cell-lines, ML-3 and HL-60, representing successively earlier stages of myeloid differentiation, contained respectively less neutral GSLs of the globoseries and an increasing proportion of (neo)lacto neutral GSLs. Granulocytes and the cell line ML-2 contained almost exclusively neutral GSLs of the (neo)lacto series.