CELL-ADHESION VIA MURINE ALPHA-4 HUMAN BETA-1 INTEGRIN CHIMERA ON TRANSFECTED K562 CELLS TO ENDOTHELIAL-CELLS

To evaluate the property of binding activity of alpha 4 beta 1 integri n in cell-cell interaction, we newly established a cell line, alpha 4m K562, by transfecting cDNA of murine integrin alpha 4 subunit into hum an erythroleukemic K562 cells, alpha 4mK562 transfectant expressed bot h murine alpha 4 and human beta 1 subunit, which generated a functiona l heterodimer. alpha 4mK562 cells more efficiently bound to murine end othelial cell lines and recombinant human TNF alpha (rhTNF)-treated hu man umbilical vein endothelial cells (HUVEC) than the parental K562 ce lls, These adhesion resulted from the interaction between alpha 4 beta 1 and VCAM-1. Interestingly, treatment with mAb against human beta 1 (4B4 clone), which has been known as inhibitory mAb, enhanced binding of alpha 4mK562 cells to rhTNF-treated HUVEC but not to murine endothe lial cells, This increase in binding induced by 4B4 mAb was completely inhibited by another mAb against human beta 1 (mAb13), but only parti ally by anti-alpha 4 mAb (PS/2), The increase in binding induced by 4B 4 mAb was also abolished by metabolic inhibitors, indicating that the increased binding is energy dependent, These observations suggest that the binding of 4B4 mAb to the chimeric alpha 4 beta 1 induces an uniq ue outside-in signaling and enhances the specific binding of alpha 4mK 562 cells to rhTNF-treated HUVEC. (C) 1996 Academic Press, Inc.