Blockade of L-selectin attenuates reperfusion injury in a rat model

Ischemia/reperfusion (I/R) injury appears to be a significant neutrophil-de pendent component and may be ameliorated by blocking leukocyte-endothelial adhesion. Using a rat extensor digitorum longus (EDL) muscle model, the pre sent study tested the hypothesis that in vivo administration of the functio n-blocking monoclonal antibody (mAb) LAM1-116 which recognizes L-selectin, a cell-surface adhesion receptor, could decrease I/R injury In 46 rats, one EDL served as a normal control and the opposite EDL underwent 3 hr of isch emia followed by 3 hr of reperfusion after pretreatment with LAM1-116 mAb, control IgG, or saline. Myeloperoxidase (MPO) activity showed only a two-fo ld increase from normal in LAM1-116-treated VR EDL while a 27-fold increase occurred in the IgG(2a) and saline groups, with a statistically significan t (p < 0.001) difference. A significantly (p < 0.05) lower wet weight ratio , improved fatigue contractile force, and less neutrophil infiltration were found in LAM1-116-treated EDL, when compared to those in control IgG- or s aline-treated EDL. The results indicate that blockade of L-selectin by LAM1 -116 mAb can effectively reduce neutrophil infiltration in reperfused skele tal muscle, thereby decreasing tissue edema and improving muscle fatigue co ntractile force. These findings may be important in understanding I/R injur y.