INTERLEUKIN-10 STIMULATION OF ENDOGENOUS NITRIC-OXIDE RELEASE FROM HUMAN SAPHENOUS VEINS DIMINISHES IMMUNOCYTE ADHERENCE

Interleukin-10 (IL-10) is described as a cytokine that exerts immune d ownregulating actions, In this regard, our study indicates that IL-10 activity on human saphenous veins is coupled to nitric oxide (NO) rele ase. We demonstrated this phenomenon by using in vitro real-time amper ometric measurement of NO levels in explanted human saphenous veins af ter IL-IO exposure, IL-10-induced NO release can inhibit the adherence of monocytes (75.7 +/- 15 cells/600 mu m(2) of endothelial surface) a nd granulocytes (65 +/- 18 cells/600 mu m(2) of endothelial surface) f rom control values (250-300 cells/600 mu m(2) of endothelial surface: p < 0.005). This inhibition is directly sensitive to NO synthase inhib ition. The specificity of the IL-10 effects is shown by its sensitivit y to antibody. In vivo measurement of LL-IO levels during and after ca rdiopulmonary bypass surgery indicated that they are higher at 6 h aft er skin closure (1,400 pg/ml) compared with levels found during surger y (300 pg/ml). We surmise that the postsurgical increase of LL-IO leve ls may be an immunoregulatory attempt to downregulate the diffuse infl ammation that has been shown to be associated with cardiopulmonary-byp ass surgery.