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

The surface expression of β2‐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‐1α, IL‐1β, and IL‐6 and tumor necrosis factor alpha (TNFα) 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‐1β or IL‐6 gene expression was never observed. Expression of IL‐1α and TNFα 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. Résumé L’expression de surface des intégrins β2 des leucocytes a été analyséc chez les patients opérés de la main ayant une ischémie induite par un garrot appliqué au niveau du bras. On a prélevé du sang aux deux bras, chez cinq patients, avant et 15 minutes après l’ischémie provoquée. Par immunofluorescence on a mis en évidence l’expression des intégrins CD18, CD11a, CD11b et CD11c. L’expression avant l’ischémie était comparable dans les deux bras. Par contre, on a retrouvé à la fin de l’ischémie provoquée (80 ± 16 minutes) une augmentat