Activation of rat basophilic leukemia cells by epsilon BP, an IgE-binding endogenous lectin

Cell Immunol. 1994 Jun;156(1):1-12. doi: 10.1006/cimm.1994.1148.


IgE-binding protein (epsilon BP) is a beta-galactoside-binding animal lectin identified by its affinity for IgE. We have reported that epsilon BP also binds the mast cell high-affinity IgE receptor (Fc epsilon RI), via lectin-carbohydrate interaction. We have now studied the physiological significance of epsilon BP-IgE-Fc epsilon RI interactions in mast cell activation using rat basophilic leukemia (RBL) cells as the model system. We report here that both unsensitized and IgE-sensitized RBL cells are activated upon exposure to epsilon BP-coated surfaces. Activation of RBL cells by the lectin epsilon BP can be significantly inhibited by appropriate saccharides. Exposure of RBL cells to epsilon BP-coated surfaces caused cell spreading similar to that caused from adherence to fibronectin-coated surfaces. However, epsilon BP by itself caused mediator release whereas fibronectin only potentiated antigen-mediated activation of RBL cells. Under appropriate conditions, epsilon BP, therefore, has the potential to activate mast cells culminating in augmentation of an inflammatory response.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Antigens
  • Antigens, Differentiation / chemistry
  • Antigens, Differentiation / pharmacology*
  • Cell Adhesion
  • Cell Degranulation / drug effects
  • Galectin 3
  • Immunoglobulin E / pharmacology
  • In Vitro Techniques
  • Lectins
  • Leukemia, Basophilic, Acute
  • Rats
  • Serotonin / metabolism
  • Signal Transduction
  • Tumor Cells, Cultured


  • Antigens
  • Antigens, Differentiation
  • Galectin 3
  • Lectins
  • Serotonin
  • Immunoglobulin E