Immune-stimulating effects of low-dose perioperative recombinant granulocyte-macrophage colony-stimulating factor in patients operated on for primarycolorectal carcinoma

Background: Surgery induces a postoperative immunosuppression, thereby poss ibly facilitating the outgrowth of pre-existing occult metastases or the se eding of disseminated tumour cells in patients with primary colorectal carc inoma operated on with curative intent. The hypothesis that adjuvant therap y with perioperative recombinant human granulocyte-macrophage colony-stimul ating factor (rhGM-CSF) would minimize postoperative immunosuppression was investigated in this pilot study. Methods: Patients were allocated randomly to receive daily subcutaneous inj ections with either saline (n = 8) or rhGM-CSF 2.8 mug per kg body-weight ( n = 8) from 3 days before operation until 4 days afterwards. Phytohaemagglu tinin (PHA) skin test reactivity, monocyte human leucocyte antigen (HLA) DR expression and the extent of the acute-phase response, by determination of white blood cell count and differentiation, plasma interleukin (IL) 6 leve ls and body temperature in the perioperative period, were examined. Results: rhGM-CSF treatment minimized postoperative suppression in PHA skin test reactivity and increased the numbers of neutrophils and monocytes whi le enhancing the expression of HLA-DR in the postoperative period. Addition ally, both postoperative plasma IL-6 levels and the incidence of fever tend ed to be higher in the rhGM-CSF group. Conclusion: in this pilot study, perioperative administration of low-dose r hGM-CSF stimulated certain immune functions that are normally depressed aft er operation. The implications for the antitumour responses directly after operation and the formation of liver metastases are currently under investi gation.