Plasma cytokine response to surgical stress in schizophrenic patients

Schizophrenic patients are reported to have immunological dysfunction, however, the immune response to surgery in schizophrenic patients remains unclear. We measured plasma interleukin-6 (IL-6), interleukin-8 (IL-8) and tumour necrosis factor-alpha (TNF-alpha) before, during and after colectomy, hemicolectomy and sigmoidectomy in 25 chronic schizophrenic patients (Group S) and 25 control patients (Group C) using ELISA assays. We could find no significant difference in the baseline plasma concentrations of IL-6, IL-8 and TNF-alpha between Group S and Group C. Plasma IL-6 concentrations (32.1 (30.3) and 15.8 (9.6) pg/ml) in Group S at the end of the operation and 24 h after surgery were significantly lower than 76.9 (37.1) and 35.1 (21.5) pg/ml of Group C. Plasma IL-8 concentration (6.1 (2.8)) in Group S at the end of the operation was significantly lower than 8.7 (4.2) pg/ml of Group C. There were no significant changes in plasma TNF-alpha concentration throughout the study period in either group. Plasma cortisol concentrations of schizophrenic patients during surgery were significantly lower than those of control patients. The plasma IL-6 concentrations correlated with plasma cortisol concentrations in either group. We conclude that proinflammatory cytokine response to abdominal surgery is inhibited in schizophrenic patients.