Serum levels of soluble IL-2 receptor α, IL-6 and IL-1 receptor antagonist in schizophrenia before and during neuroleptic administration

Serum levels of interleukin-2 soluble receptor alpha (IL-2sR alpha), interleukin-6 (IL-6) and interleukin-l receptor antagonist (IL-1ra) were determined both before and during neuroleptic administration in an 8-week treatment protocol for schizophrenia. In comparison with a control group, schizophrenia patients showed significantly higher serum levels of IL-2sR alpha, IL-6 and IL-1ra at weeks 0, 1, 4 and 8, and there was a significant negative correlation between the serum level of IL-2sR alpha at week 1 and the age at illness onset. Those of the schizophrenia patients who were neuroleptic-naive had significantly higher pretreatment serum levels of IL-2sR alpha, IL-6 and IL-1ra than the controls. There were significant positive correlations between the IL-2sR alpha levels at weeks 0 and 1, and the psychopathology scores, evaluated using the positive and negative syndrome scale at week 4. IL-6 levels at weeks 0, 1 and 4 were significantly and positively correlated with the duration of illness. The IL-1ra level at week 1 was significantly and positively correlated with positive symptoms at week 1. The present study supports the suggestion that changes in the immune system are involved in the pathophysiology of schizophrenia. (C) 1999 Published by Elsevier Science B.V. All rights reserved.