Patterns of changes in neutrophil adhesion molecules during normothermic cardiopulmonary bypass : A clinical study

The adhesion of activated neutrophils to endothelial cells is a key feature of the inflammatory re- sponse to cardiopulmonary bypass (CPB) because it "unlocks" a cas- cade of cytotoxic events. This adhe- sion is made possibly by the sequen- tial involvement of two sets of neu- trophil cell surface receptors: L-selectin and/32 integrins (CD 11 a/CD 18; CD 11 b/CD 18; CD 11 c/CD 18). We have assessed the changes in the expression of these adhesion molecules in ten pa- tients who underwent various open- heart procedures with the use of "warm" (33.4 °-37 °C) CPB. Arterial blood samples were obtained before, during and after bypass and pro- cessed for immunofluorescent flow cytometric analysis. CD 11 a expres- sion remained unchanged throughout the study period. Conversely, CD 11 b drastically increased early after the onset of bypass (at 15 rain on bypass: 172 + 17 (mean fluores- cence (arbitrary units), mean +_ SEM) versus 63 +_ 13 before bypass, P < 0.02) and was still markedly ele- vated 30 min after the end of bypass (160+38, P<0.05 versus the pre-by- pass value). CD 11 c expression underwent a similar upregulation (at 15 rain of bypass: 54_+5 versus 34+_5 at baseline, P<0.01). L-selec- tin expression did not change signifi- cantly during the period of observa-