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 surface is mediated by B-2 integrins. We studied integrin expression and monoclonal antibody inhibition of peripheral blood leukocyte (PBL) binding 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 inhibition of leukocyte adherence was studied for up to 30 min using flow cytometry. ePTFE segments were implanted subcutaneously in SKH-1 mice and PBL harvested 4 days later. PBL binding of monoclonal antibodies against CD11b was measured using how cytometry. CD18 was constitutively expressed 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 monoclonal antibody binding of CD11b (P < 0.0001) compared to sham, Staphylococcus aureus alone, and the combination of ePTFE and S. aureus. In conclusion, leukocyte integrins play a central role in the interaction between PBLs and ePTFE as measured by binding of monoclonal antibodies and inhibition of PBL adherence. This is also true in vivo since PBL increase CD11b expression four times when ePTFE is compared to sham. These observations indicate a potential role in vivo for B-2 integrins in vascular prosthetic infections. (C) 1996 Academic Press, Inc.