ADHESION MOLECULES IN HEMATOPOIETIC-CELLS

Interaction with stromal cells is known to be crucial for growth and d ifferentiation of hematopoietic cells. To characterize adhesion molecu les involved in this interaction, we examined adhesion of a panel of l ymphoid, myeloid, and mast cell lines with stromal cells. We found tha t very late antigen-4 (VLA-4) and vascular cell adhesion molecule 1 (V CAM-1) were major adhesion molecules in lymphoid and myeloid cells, wh ereas myeloma cells adhered to stromal cells through hyaluronate. We i nvestigated regulation of VLA-4 during differentiation of myeloid cell s using a neutrophil precursor cell line, L-G3. Differentiation of neu trophils induced by granulocyte colony-stimulating factor was accompan ied with down-regulation of VLA-4. Induced L-G3 cells adhered to strom al cells in proportion to the expression of VLA-4. Mast cells used two mechanisms to adhere to fibroblasts and stromal cells. They adhered t o fibronectin through VLA-5 when stimulated with steel factor and also directly to membrane-anchored steel factor through c-kit.