Surgery-induced decline in circulating dendritic cells in operable cancer patients: A possible explanation of postoperative immunosuppression

Background/Aims: The recent advances in the immunobiology of tumor have demonstrated the essential role of dendritic cells in anticancer immunity. Dendritic cells activate anticancer immunity by secreting interleukin-12 and by activating T helper lymphocytes, with the following production of interleukin-2. Since surgery-induced immunosuppression has been proven to be associated with a decline in the blood levels of both interleukin-2 and interleukin-12, it could depend at least in part on a transient deficiency of dendritic cells system. Unfortunately, at present there are no data about changes in circulating dendritic cell number during the postoperative period. This preliminary study was performed to evaluate the influence of surgery on dendritic cell number in the peripheral blood. Methodology: The study included 14 consecutive operable gastrointestinal tract cancer patients, who were evaluated before and at day 7 of the post-operative period. The control group consisted of 50 healthy subjects. Immature (CD 123 + ) and mature (CD 11 + ) dendritic cell subsets were measured by FACS and monoclonal antibodies. Results: Cancer patients showed a significantly lower mean number of immature dendritic cells with respect to that found in controls. The mean number of mature dendritic cells was also lower in patients than in controls, without, however, significant differences. Finally, surgery induced a statistically significant decline in the mean number of both immature and mature dendritic cells, and the decrease was particularly pronounced for immature dendritic cells. Conclusions: In addition to the well-demonstrated surgery-induced lymphocytopenia, this preliminary study shows that the surgical treatment may determine a significant decrease in circulating immature and mature dendritic cells. Because of the fundamental role of dendritic cells in regulating the immune responses, surgery-induced decline in circulating dendritic cells number could play a role in determining the immunosuppressive status, which characterizes the postoperative period.