Increased surface expression of CD18 and CD11b in leukocytes after tourniquet ischemia during elective hand surgery.

The surface expression of beta2-integrins was investigated in leukocytes from patients undergoing ischemia induced by tourniquet application for elective hand surgery. Blood samples were obtained before initiation, at the end of ischemia, and after 15 minutes of reperfusion from ischemic and contralateral arms of five patients. Comparable expression of CD18, CD11a, CD11b, and CD11c could be detected by immunofluorescence in leukocytes from samples drawn from either arm before tourniquet application. In contrast, a significant increase in the expression of CD18 was detectable in monocytes, granulocytes, and lymphocytes from the ischemic arm compared with that in the nonischemic contralateral control, at the end of the ischemia time (80 +/- 16 minutes). A significantly increased expression of CD11b, but not CD11a or CD11c, determinants was also observed in granulocytes and monocytes. Concomitantly, a significant reduction in the percentages of granulocytes in samples from ischemic areas was detectable. After 15 minutes of reperfusion, differences in the expression of these adhesion molecules were no longer significant. The expression of the genes encoding interleukins IL-1alpha, IL-1beta, and IL-6 and tumor necrosis factor alpha (TNFalpha) proinflammatory cytokines was also studied by reverse polymerase chain reaction (rPCR) in peripheral blood mononuclear cells (PBMCs) obtained from the same samples in three patients. IL-1beta or IL-6 gene expression was never observed. Expression of IL-1alpha and TNFalpha genes, as detected in two patients, was not related with induction of ischemia. However, in these patients expression of one or both these genes was observed in samples derived from the ischemic but not the control arm after 15 minutes of reperfusion. These data document that overexpression of adhesion molecules and sequestration of leukocytes take place following short ischemia times, as routinely applied clinically for minor surgical procedures.