THE BIOLOGIC ROLE OF B-2 INTEGRINS IN THE HOST RESPONSE TO EXPANDED POLYTETRAFLUOROETHYLENE

We hypothesized that the adherence of leukocytes to a vascular graft s urface is mediated by B-2 integrins. We studied integrin expression an d monoclonal antibody inhibition of peripheral blood leukocyte (PBL) b inding in vitro and CD11b expression in vivo. Human PBL were grown on ePTFE in culture and labeled with monoclonal antibodies to CD11a, -b, -c, and/or CD18. Percentage of monoclonal antibody binding and inhibit ion of leukocyte adherence was studied for up to 30 min using flow cyt ometry. ePTFE segments were implanted subcutaneously in SKH-1 mice and PBL harvested 4 days later. PBL binding of monoclonal antibodies agai nst CD11b was measured using how cytometry. CD18 was constitutively ex pressed and CD11a decreased over time. CD11b increased from 41 to 62% and CD11c increased transiently (P < 0.003, P < 0.005). Inhibition of PBL adherence was greatest by CD11b (34%) and CD11b + CD18 (57%) (P < 0.005, P < 0.025). Implanted ePTFE caused a fourfold increase in PBL m onoclonal antibody binding of CD11b (P < 0.0001) compared to sham, Sta phylococcus aureus alone, and the combination of ePTFE and S. aureus. In conclusion, leukocyte integrins play a central role in the interact ion between PBLs and ePTFE as measured by binding of monoclonal antibo dies and inhibition of PBL adherence. This is also true in vivo since PBL increase CD11b expression four times when ePTFE is compared to sha m. These observations indicate a potential role in vivo for B-2 integr ins in vascular prosthetic infections. (C) 1996 Academic Press, Inc.