LIGAND-INDUCED ADHESION TO ACTIVATED ENDOTHELIUM AND TO VASCULAR CELL-ADHESION MOLECULE-1 IN LYMPHOCYTES TRANSFECTED WITH THE N-FORMYL PEPTIDE RECEPTOR

Binding of FMLP to the neutrophil N-formyl peptide receptor (FPR) tran smits signals through pertussis toxin-sensitive G proteins triggering Ca2+ flux, superoxide production, granule exocytosis, and neutrophil a ggregation and adhesion involving the beta 2 (CD18) integrins. Express ion of the FPR in mouse fibroblasts or human kidney cells has been sho wn to confer an N-formyl peptide-inducible Ca2+ flux in transfectants. Here we demonstrate that the transfected receptor can also support li gand-induced alterations in cellular adhesion. We established stable t ransfectants of mouse L1-2 pre-B cells with cDNA for human FPR (L1-2 F PR cells). The transfectants bind N-formyl-Nle-Leu-Phe-Nle-Tyr-Lys-flu orescein with 1.4 X 10(5) sites per cell and a dissociation constant o f 3.3 nM. Stimulation with FMLP induces a transient Ca2+ flux. FMLP al so triggers adhesion of L1-2 FPR cells to TNF-alpha- or LPS-activated bEnd3 cells (mouse brain-derived endothelial cells) and to purified mo use VCAM-1. Binding is inhibited by Abs to VCAM-1 and to the alpha-cha in of its lymphocyte receptor (the alpha 4 beta 1 integrin, VLA-4). St imulation with FMLP does not induce a change in cell surface expressio n of alpha 4. Induced adhesion to VCAM-1 is rapid, detectable at the e arliest times measurable (30 to 60 s after FMLP addition), and is inhi bited by pertussis toxin. We conclude that FPR can mediate integrin ac tivation not only in neutrophils but also in lymphocytes, and can trig ger rapid adhesion via lymphocyte alpha 4 beta 1. The adhesion of lymp hocytes is critical to their migration and targeting; our results sugg est the possibility of manipulating adhesive responses through express ion of chemoattractant receptors in lymphoid cells engineered for cell ular therapy, allowing targeted adhesion and potentially migration in response to locally administered ligands.