Hemoperfusion with polymyxin B-immobilized fibers reduced the number of CD16+CD14+ monocytes in patients with septic shock

Background: CD16(+)CD14(+) monocytes dramatically increase in number in patients with severe infection. Hemoperfusion with PMX-F ( direct hemoperfusion with polymyxin B immobilized fibers) has been reported to be a safe and effective treatment for patients with septic shock, although the molecular mechanism that accounts for its effectiveness is still unclear. The purpose of this study was to quantify the number of CD16(+)CD14(+) monocytes in patients with an intra-abdominal infection and to evaluate the effects of PMX-F treatment on clinical parameters and leukocyte surface antigen expression in these patients. Materials and Methods: Seventeen septic patients who had an intra-abdominal infection were enrolled in this study; 7 of these patients received PMX-F treatment. Peripheral blood samples were obtained immediately after admission, and were also collected from the above 7 patients before, during, and immediately after their PMX-F treatment. The expression of CD14, CD16, and Toll-like receptor (TLR)-4 on these patients' monocytes was evaluated using flow cytometry. In addition, lipopolysaccharide (LPS)-induced production of TNF-alpha and IL-1beta by these cells was measured by ELISA. Results: Monocytic expression of CD16 and TLR-4 was significantly greater in septic patients than in healthy controls, and their proportion of CD16(+) CD14(+) monocytes was similarly elevated. LPS-induced production of TNF-alpha and IL-1beta by peripheral blood mononuclear cells (PBMCs) of septic patients was significantly reduced compared to controls. Furthermore, there was a reduction in the proportion of CD16+ CD14+ monocytes during PMX-F treatment, and in the expression of TLR-4 on monocytes after PMX-F treatment. Conclusions: These results showed that the number of peripheral blood CD16(+) CD14(+) monocytes and monocytic TLR-4 expression were markedly increased, and the production of pro-inflammatory cytokines in response to LPS significantly reduced in patients with sepsis. PMX-F treatment was found to be effective in reducing the number of CD16(+) CD14(+) monocytes and in decreasing the monocytic expression of TLR-4 in patients with septic shock.