A Comparison of Monocyte Counts and Ex Vivo and In Vitro Monocyte Cytokine Production After Major Surgical Trauma

BackgroundImpaired function of cluster of differentiation 14-positive (CD14+) monocytes (MOs) after major surgical trauma is believed to predispose to infectious complications. Postoperative decreases in human leukocyte antigen (HLA)-DR expression, tumor necrosis factor-alpha (TNF-α) production and interleukin (IL)-12 synthesis have been reported. There are no studies comparing absolute MO counts and MO cytokine synthesis in peripheral blood and stimulated cultures.MethodsThe study group included 10 low-risk patients undergoing elective cardiac surgery with extracorporeal circulation. Preoperatively (d0) and on the first (d1) and third (d3) postoperative d, we analyzed leukocyte counts, CD14+ MO absolute counts, HLA-DR expression, and stimulated IL-12 and TNF-α synthesis using flow cytometry. In addition, IL-12 and TNF-α release in stimulated whole blood cultures was assayed.ResultsWhereas the absolute numbers of leukocytes and CD14+ MOs were significantly elevated, HLA-DR expression was suppressed postoperatively. The proportion of TNF-α- and IL-12-producing MOs was reduced after surgery. This, however, led to a significant postoperative decrease only in the absolute numbers of peripheral blood IL-12+ MOs. IL-12 secretion was postoperatively reduced in whole blood cultures. The IL-12-synthesizing capacity of IL-12+ MOs was significantly reduced only on d1.ConclusionsThe immediate postoperative period is associated with an increase in the absolute MO numbers and an impairment of MO function, which is reflected in a reduced capacity to synthesize IL-12 and TNF-α and a decreased ability to express HLA-DR and present antigens. Whereas the cytokine-producing capacity returns to normal levels on d3, the suppression of HLA-DR expression persists.