globotriaosylceramide and Lymphoma

We have used two methods to evaluate the level of expression of Gb3Cer in several human leukaemia/lymphoma cell lines representative of the myeloid (K562, KG-1, HL-60, and lymphoid (Reh, Daudi, Raji, RPMI 8226, CCRF-CEM, MOLT-4) lineages blocked at varied stages of differentiation. TLC immunostaining of glycolipid extracts with a monoclonal antibody, 12-101, and FACS analysis with the same antibody were used to demonstrate that the expression of Gb3Cer in neoplastic myeloid and lymphoid cells is both lineage and differentiation dependent. As a possible control point in the regulated expression of Gb3Cer we have investigated the first committed step in the synthesis of globo series glycosphingolipids that involves UDP-Gal:LacCer alpha (1,4)-galactosyltransferase (alpha 1,4GalT). We present the first characterization of this enzyme in a human myeloid cell line using an ELISA-based assay, which was subsequently used to measure alpha 1,4GalT activity in the human leukaemia/lymphoma cell lines. In general, there is a positive correlation between the levels of endogenous Gb3Cer and the level of the alpha 1,4 GalT activity. However, in two cases (KG-1 and CCRF-CEM) the level of enzyme activity did not correspond to the level of Gb3Cer expression.

Topics: Carbohydrate Conformation; Carbohydrate Sequence; Cell Differentiation; Cell Line; Chromatography, Thin Layer; Flow Cytometry; Galactosyltransferases; Glycosphingolipids; HL-60 Cells; Humans; Leukemia; Lymphoma; Molecular Sequence Data; Monocytes; Trihexosylceramides; Tumor Cells, Cultured

The purpose of this study was to isolate mouse monoclonal antibodies (MAbs) recognizing Gal alpha 1-4Gal beta 1-4Glc (Pk, CD77), which has been described as a Burkitt's-lymphoma-associated antigen. Three IgGI MAbs reactive with Pk were developed using a synthetic glycoconjugate as immunogen and a filter immunoplaque screening assay. One MAb (PK67) was characterized by immuno-thin-layer chromatography, ELISA and competition assays using neutral glycolipids from various sources and a variety of carbohydrates and glycoproteins. Epitope analysis showed that all 3 carbohydrates moieties are required in PK67 binding. No cross-reactivity was observed with closely related carbohydrate structures, with the exception of Gal alpha 1-4Gal beta 1-4GlcNAc. However, the reactivity with this structure was several orders of magnitude lower than with Pk. Immunohistochemical analysis of fresh-frozen tissue specimens showed that Gb3 is widely expressed: prominent staining was observed in many normal tissues, e.g., kidney and gastric tissue and on capillary endothelial cells. In lymph nodes, very weak staining of a few B cells was observed. Flow cytometric analysis of hematopoietic neoplasms showed Gb3 expression on B-cell neoplasms, particularly those with committed B-cell phenotype indicating that, in addition to earlier reports of Gb3 expression on Burkitt's lymphoma, Gb3 is present on other committed B-cell neoplasms.

Topics: Animals; Antibodies, Monoclonal; Antigens, CD; Carbohydrate Sequence; Carbohydrates; Cross Reactions; Enzyme-Linked Immunosorbent Assay; Glycolipids; Glycoproteins; Humans; Hybridomas; Immunoenzyme Techniques; Leukemia; Lymphoma; Mice; Mice, Inbred BALB C; Molecular Sequence Data; Neoplasms; Organ Specificity; Reference Values; Trihexosylceramides

Two Escherichia coli cytotoxins (verotoxins 1 and 2) have been previously implicated in the cytopathology of the Hemolytic Uremic Syndrome. We have examined the glycolipid binding specificity of verotoxin (VT)2. This toxin specifically binds to globotriosyl ceramide (galactose alpha 1-4 galactose beta 1-4 glucosyl ceramide). Removal, or substitution of the terminal a galactose residue with N-acetyl galactosamine in beta 1-3 linkage, deletes binding activity. The toxin does not recognize similar terminal a galactose residues on a glycoglycerolipid. Thus the binding specificity of VT2 is the same as previously reported for VT1. Liposomes containing globotriosyl ceramide are able to specifically remove VT1 and VT2 cytotoxicity and cell lines selected in vitro for resistance to VT1 are cross resistant to VT2.

Topics: Bacterial Toxins; Cell Line; Cytotoxins; Escherichia coli; Globosides; Glycosphingolipids; Humans; Liposomes; Lymphoma; Phospholipids; Receptors, Cell Surface; Receptors, Immunologic; Shiga Toxin 1; Trihexosylceramides