Background: The immune reaction of the peritoneum to growing gastrointestinal neoplasms remains unclear. We investigated mobilization of immune cells in peritoneal fluid of gastric and colon cancer, phenotypes and level of activation of recruited cells, and concentration of cellular and peritoneal fluid cytokines.
Methods: Peritoneal cells (PCs) were obtained intraoperatively by peritoneal lavage from 18 patients with adenocarcinoma of the stomach and 32 patients with adenocarcinoma of the colon (all were stage T2N0M0) and 52 patients who underwent elective cholecystectomy as control subjects.
Results: The number of PCs harvested from cancer patients was 25 times greater than from control patients (P < .001). In the patients with colon cancer, the percentage of CD68+ macrophages was 1.2 times, of CD14+ monocytes was 2.3 times, and of CD15+ granulocytes was 3 times greater than in control patients (all P < .05). The percentage of HLA DR+ cells exceeded the control values by a factor of 2; and within this population, the percentage of CD3+ HLA DR+ cells exceeded control patients by a factor of 3 (P < .05). The percentage of cytokine-producing cells was greater than in control patients, with values 2 times higher for interleukin (IL)-1, 2.5-times for IL-6, and 6-times for IL-8 (P < .05). The concentration of IL-1 in peritoneal fluid exceeded control values by a factor of 2.2, of IL-6 by a factor of 5.0, of IL-8 by a factor of 3, and of monocyte chemotactic protein-1 by a factor of 2.0 (P < .05). In the patients with gastric cancer, the values for mobilized PC granulocytes were 1.5 times greater than in control patients (P < .05). The frequency rate of cytokine-producing cells remained close to control values. The concentration of peritoneal cytokines did not exceed normal values for IL-1 but was 4 times higher for IL-6 and 2 times higher for IL-8 and monocyte chemotactic protein-1 (all P < .05). When the cancer groups were compared, there was evidently more activated myeloid- and cytokine-producing PC in the patients with colon cancer than in patients with gastric cancer. There was no correlation between the blood and PC phenotype frequency.
Conclusion: Patients with T2N0M0 colon cancer and to lesser extent gastric cancer evoke a slight but measurable mobilization and activation of PCs.