Adhesion molecules in hematopoietic cells.

Interaction with stromal cells is known to be crucial for growth and differentiation of hematopoietic cells. To characterize adhesion molecules involved in this interaction, we examined adhesion of a panel of lymphoid, myeloid, and mast cell lines with stromal cells. We found that very late antigen-4 (VLA-4) and vascular cell adhesion molecule 1 (VCAM-1) were major adhesion molecules in lymphoid and myeloid cells, whereas myeloma cells adhered to stromal cells through hyaluronate. We investigated regulation of VLA-4 during differentiation of myeloid cells using a neutrophil precursor cell line, L-G3. Differentiation of neutrophils induced by granulocyte colony-stimulating factor was accompanied with down-regulation of VLA-4. Induced L-G3 cells adhered to stromal cells in proportion to the expression of VLA-4. Mast cells used two mechanisms to adhere to fibroblasts and stromal cells. They adhered to fibronectin through VLA-5 when stimulated with steel factor and also directly to membrane-anchored steel factor through c-kit.