Plasma levels of interleukin-6 and tumor necrosis factor alpha in chronic schizophrenia: effects of clozapine treatment

Psychiatry Res. 1997 Jun 16;71(1):11-7. doi: 10.1016/s0165-1781(97)00036-x.


Plasma levels of interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF alpha) were assessed in 17 chronic schizophrenic patients who had been drug-free for 3 weeks and in 17 age- and sex-matched healthy subjects. Plasma concentrations of both cytokines were measured again in 12 patients after a 10-week treatment with clozapine. Compared with healthy controls, drug-free schizophrenic patients exhibited similar plasma IL-6 concentrations, but significantly higher levels of TNF alpha. After clozapine treatment, blood concentrations of TNF alpha fell to normal levels. These preliminary data support an immune activation in drug-free schizophrenic patients and an effect of clozapine on immune parameters.

MeSH terms

  • Adult
  • Antipsychotic Agents / therapeutic use*
  • Clozapine / therapeutic use*
  • Female
  • Humans
  • Interleukin-6 / blood*
  • Male
  • Schizophrenia / blood*
  • Schizophrenia / drug therapy
  • Tumor Necrosis Factor-alpha / analysis*


  • Antipsychotic Agents
  • Interleukin-6
  • Tumor Necrosis Factor-alpha
  • Clozapine