Lower serum cytokine levels in smokers than nonsmokers with chronic schizophrenia on long-term treatment with antipsychotics.
OBJECTIVE
Schizophrenia is associated with various abnormalities in the immune system. Suppression of inflammatory cytokines by cigarette smoke is well-established. The purpose of this study was to determine any differences in cytokine profiles in smokers and nonsmokers with schizophrenia and whether there were any relationships among altered cytokine profiles and psychopathological symptoms.


METHODS
Serum interleukin (IL)-2, IL-6, IL-8, and tumor necrosis factor (TNF)-alpha levels were measured in 96 male inpatients with DSM-IV schizophrenia: 66 smokers and 30 nonsmokers. Symptoms were assessed with the Positive and Negative Syndrome Scale (PANSS).


RESULTS
The positive PANSS symptoms were lower in smokers than nonsmokers, while the negative symptoms were lower in those who smoked more cigarettes. Cytokine levels were positively correlated: IL-2 level with IL-6 and IL-6 with both IL-8 and TNF-alpha. Both IL-2 and IL-6, but not IL-8 or TNF-alpha, were significantly lower in smokers than nonsmokers (p < 0.002; p < 0.01). Lower IL-2 levels correlated with fewer negative symptoms and with smoking more cigarettes.


CONCLUSIONS
The fewer positive symptoms in smokers and fewer negative symptoms in those who smoked more cigarettes may be associated with nicotine-induced suppression of some inflammatory cytokines.
Zhang
Xiang Yang
XY
Menninger Department of Psychiatry and Behavioral Sciences, Baylor College of Medicine, VA Medical Center, Houston, TX 77030, USA. xyzhang@bcm.edu
Cao
Lian Yuan
LY
Song
Cai
C
Wu
Gui Ying
GY
Chen
Da Chun
DC
Qi
Ling Yan
LY
Wang
Fan
F
Xiu
Mei Hong
MH
Chen
Song
S
Zhang
Yingyang
Y
Lu
Lin
L
Kosten
Therese A
TA
Kosten
Thomas R
TR
D000367:Age Factors; D014150:Antipsychotic Agents / Q000627:therapeutic use*; D002908:Chronic Disease; D003024:Clozapine / Q000097:blood / Q000627:therapeutic use; D039721:Diagnostic and Statistical Manual of Mental Disorders; D004334:Drug Administration Schedule; D006801:Humans; D007378:Interleukins / Q000097:blood* / Q000737:chemistry*; D008297:Male; D008875:Middle Aged; D011569:Psychiatric Status Rating Scales; D012559:Schizophrenia / Q000097:blood* / Q000175:diagnosis / Q000188:drug therapy*; D012907:Smoking / Q000097:blood*; D016540:Smoking Cessation / Q000523:psychology; D013997:Time Factors; D016896:Treatment Outcome; D014409:Tumor Necrosis Factor-alpha / Q000097:blood* / Q000737:chemistry
D014150:Antipsychotic Agents; D007378:Interleukins; D014409:Tumor Necrosis Factor-alpha; D003024:Clozapine