EX-VIVO ANALYSIS OF LEUKOCYTE HYDROGEN-PEROXIDE PRODUCTION USING A BI-PLATE MODEL IN MICE

Implantation of artificial materials is followed by inflammation and w ound healing, where phagocytic cells play an important role. The mecha nisms whereby the implant surface may elicit and modulate leukocyte fu nctions in vivo are not understood, partly due to the technical diffic ulties of examining the local inflammatory events in vicinity of the m aterial-tissue interface with conventional biochemical and immunologic al techniques. In the present study a newly developed biplate implant was inserted subcutaneously in the mouse. Leukocytes from the local in flammatory exudate and leukocytes associated to the surface of the imp lants were retrieved after 1 and 6 days and separately assayed with re spect to hydrogen peroxide (H2O2) production ex vivo. Implantation cau sed a local accumulation of predominantly mononuclear cells in the sur rounding subcutaneous tissue. The H2O2 production was found to be low in both the subcutaneous exudate and the implant-associated leukocytes , irrespective of implant material and implantation times. However, ex vivo-stimulation with phorbol myristate acetate (PMA) caused an enhan ced H2O2, production. These observations show that biplate implants do not maximally activate the oxidative metabolism of the recruited leuk ocytes. The exudate leukocytes were more responsive to PMA stimulation in comparison with implant-associated leukocytes, indicating that pro perties of the implant surface and possibly surface-associated protein s could modify the responsiveness of the phagocytic cells at the impla nt site. Our results suggest that the present biplate model may be sui table for further studies on local production of oxygen metabolites an d function of leukocytes at implanted biomaterials. (C) 1996 Wiley-Lis s, Inc.