Abstract 3536: Aprotinin Blocks Leukocyte Extravasation into Tissues in Patients Undergoing Cardio-Thoracic Surgery with Cardiopulmonary Bypass
Introduction Aprotinin (Trasylol), used clinically to reduce transfusion requirement and the inflammatory response to cardiopulmonary bypass (CPB), has been shown to attenuate leukocyte extravasation in animals and in vitro. In order to examine leukocyte trafficking in humans we have employed the cantharidin skin blister technique in patients undergoing coronary artery bypass grafting (CABG) surgery with CPB to test the hypothesis that:
surgery stimulates leukocyte extravasation into skin and
this is inhibited by aprotinin.
Methods CABG patients were randomized to receive placebo (saline infusion during CPB [n=8]) or aprotinin (2X106 kallikrein inhibitor units [KIU] aprotinin in pump prime, 2X106 KIU loading dose, followed by 0.5X106 KIU/h infusion [n=8]). Duplicate skin blisters were initiated immediately prior to surgery by topical application of cantharidin to the forearm. Blisters were allowed to develop peri-operatively for 5h before analysis of leukocytes in blister fluid by flow cytometry and inflammatory mediators by enzyme linked immunosorbent assay. As an internal control, analagous skin blisters were performed the day prior to surgery.
Results CABG surgery enhanced trafficking of activated (CD11b+/CD62L-) neutrophils and monocytes into skin blisters in the placebo group (0.74 ± 0.33 x 106 [mean ± SD] total cells per blister pre-op vs. 3.45 x 106 ± 1.07 peri-op; P=0.017) but this was significantly attenuated in patients receiving aprotinin (1.17 ± 0.25 x 106 cells pre-op vs. 1.36 ± 0.31 x 106 peri-op; P=0.042 comparing placebo vs. aprotinin peri-op). Proinflammatory interleukin-8 and tumor necrosis factor alpha levels in blister fluid were also significantly diminished in aprotinin versus placebo (P<0.05).
Conclusions This study has demonstrated for the first time that leukocyte extravasation due to CPB is blocked by aprotinin clinically, thus extending the anti-inflammatory mechanism of action of this drug. Our results also establish the cantharidin skin test as a novel translational tool capable of analyzing pharmacointervention at the diapedesis step, with implications beyond cardiac surgery for anti-inflammatory drug development.