i(3)so3-galactosylceramide and Lymphoma

Sulfatide has been reported to activate leukocytes through L-selectin. Here we provide evidence that sulfatide binds to and activates leukocytes through both L-selectin-dependent and -independent pathways. Rat leukocytes of various sources shed surface L-selectin after phorbol myristate acetate (PMA) treatment, however, these cells retained the ability to bind sulfatide. In addition, sulfatide also bound to an L-selectin-negative cell line EL-4, and the binding was up-regulated by PMA. Sulfatide induced aggregation of L-selectin-positive lymphocytes, which was highly dependent on divalent cations, protein tyrosine kinases (PTK), and protein kinase C (PKC), but was independent of beta1 and beta2 integrins. In contrast, sulfatide-induced EL-4 cell aggregation required an LFA-1/ICAM-1 adhesion pathway but not PTK and PKC. A sulfatide receptor of 65 kDa was isolated from EL-4 cells. Taken together, this study suggests that sulfatide can bind to and activate leukocytes through an L-selectin-independent molecule and triggers signal transduction pathways different from those induced by L-selectin activation.

Topics: Animals; Antibodies, Monoclonal; Binding Sites; Cations, Divalent; Cattle; CD18 Antigens; Cell Adhesion; Cell Aggregation; Cells, Cultured; Consensus Sequence; Culture Media; Culture Media, Serum-Free; Dogs; Endothelium, Vascular; Enzyme Inhibitors; Fetal Blood; Integrin beta1; Intercellular Adhesion Molecule-1; Jugular Veins; L-Selectin; Leukocytes; Lymph Nodes; Lymphocyte Function-Associated Antigen-1; Lymphoma; Male; Molecular Weight; Neoplasm Proteins; Protein Kinase C; Protein-Tyrosine Kinases; Rats; Rats, Wistar; Receptors, Cell Surface; Signal Transduction; Specific Pathogen-Free Organisms; Sulfoglycosphingolipids; T-Lymphocytes; Tetradecanoylphorbol Acetate; Tumor Cells, Cultured