Abdominal Surgical Interventions: Local and Systemic Consequences for the Immune System--a Prospective Study on Elective Gastrointestinal Surgery

Background: Little is known about the local accumulation and function of immune cells in peritoneal fluid after elective surgery of the upper and lower gastrointestinal tract. Our study was designed to investigate whether systemic immune cell response mirrors the local response. We focused on the cytokines interleukin (IL)-6 and tumor necrosis factor (TNF)-alpha and on monocytes, natural killer (NK) cells, and T cells that play an important role in eliciting the innate and adaptive immune response.

Methods: Blood samples were taken prospectively from 25 patients 24 h before surgery, as well as 24 h and 48 h afterward. Abdominal drainage fluids were collected intraoperatively 1 h after the abdomen was opened and 24 h and 48 h postoperatively. Apart from the white blood cells, intracellular T-helper-cell (TH1/TH2) cytokine production (interferon-gamma, IL-2, IL-4, IL-13) and HLA-DR on monocytes were measured by four-color flow cytometry, IL-6, and TNF-alpha with the fast immunoluminescence method.

Results: Cells of the innate immune system (NK cells, monocytes, NK-T cells, CD5(+) B cells) rapidly decreased in abdominal fluids (P < 0.05: +24 h; +48 h) after surgery, which was paralleled by a concomitant decline in peripheral blood. The percentage of abdominal interferon-gamma, IL-2, IL-4, and IL-13-producing TH cells increased in a way that distinctly counteracted the decrease of the natural immune cells. HLA-DR expression on monocytes in peripheral blood declined significantly (P < 0.05: +24 h; +48 h). In contrast, monocytes in abdominal fluids had high HLA-DR expression. Furthermore, abdominal fluids contained significantly higher concentrations of TNF-alpha (P < 0.05: +24 h; +48 h) and IL-6 (P < 0.05: +24 h) compared with peripheral blood.

Conclusions: Specific immune cell recruitment and cytokine production play an important role in post-trauma events. Measuring distinct local immune cell repertoires and cytokines provides answers as to how the different phases of postoperative immune events proceed. The evaluation of the local response may provide additional criteria for the evaluation of operative trauma. This knowledge may be helpful in detecting postoperative pathological aberrancies.