INCREASED SURFACE EXPRESSION OF CD18 AND CD11B IN LEUKOCYTES AFTER TOURNIQUET ISCHEMIA DURING ELECTIVE HAND SURGERY

The surface expression of beta(2)-integrins was investigated in leukoc ytes from patients undergoing ischemia induced by tourniquet applicati on for elective hand surgery. Blood samples were obtained before initi ation, at the end of ischemia, and after 15 minutes of reperfusion fro m ischemic and contralateral arms of five patients. Comparable express ion of CD18, CD11a, CD11b, and CD11c could be detected by immunofluore scence in leukocytes from samples drawn from either arm before tourniq uet application. In contrast, a significant increase in the expression of CD18 was detectable in monocytes, granulocytes, and lymphocytes fr om the ischemic arm compared with that in the nonischemic contralatera l control, at the end of the ischemia time (80 +/- 16 minutes). A sign ificantly increased expression of CD11b, but not CD11a or CD11c, deter minants was also observed in granulocytes and monocytes. Concomitantly , a significant reduction in the percentages of granulocytes in sample s from ischemic areas was detectable. After 15 minutes of reperfusion, differences in the expression of these adhesion molecules were no lon ger significant. The expression of the genes encoding interleukins IL- 1 alpha, IL-1 beta, and IL-6 and tumor necrosis factor alpha (TNF alph a) proinflammatory cytokines was also studied by reverse polymerase ch ain reaction (rPCR) in peripheral blood mononuclear cells (PBMCs) obta ined from the same samples in three patients. IL-1 beta or IL-6 gene e xpression was never observed. Expression of IL-1 alpha and TNF alpha g enes, as detected in two patients, aas not related with induction of i schemia. However, in these patients expression of one or both these ge nes was observed in samples derived from the ischemic but not the cont rol arm after 15 minutes of reperfusion. These data document that over expression of adhesion molecules and sequestration of leukocytes take place following short ischemia times, as routinely applied clinically for minor surgical procedures.