PHENOTYPIC ALTERATIONS IN CIRCULATING MONOCYTES INDUCED BY OPEN-HEART-SURGERY USING HEPARINIZED AND NONHEPARINIZED CARDIOPULMONARY BYPASS SYSTEMS

In this study of 31 patients with coronary bypass surgery, we used flo w cytometry to compare heparin-coated and noncoated cardiopulmonary by pass systems on leukocyte activation. We found significant differences between the groups during bypass, with activation of the complement s ystem, measured as elevated levels of C3a desArg, upregulation of gran ulocyte beta(2) integrin (CD11b), and a loss of circulating monocytes when noncoated systems were used. In both groups an early increase in the monocyte cell surface CD62L expression was obvious while the perce ntage of human leukocyte antigen (HLA)-DR positive monocytes did not a lter. The morning after the operation, leukocytosis was present, toget her with a highly significant reduction in the monocyte expression of CD11b and HLA-DR, indicating the recruitment to the peripheral blood o f cells with altered phenotypes. This alteration in phenotype on poten t inflammatory cells may be one part of the impaired function of the i mmunological system reported after major surgery.