Soluble IL-6 receptors in the serum and cerebrospinal fluid of paranoid schizophrenic patients

Soluble Interleukin-6 receptor (sIL-6R) levels are strongly related to the levels of Interleukin-6 (IL-6), and sIL-6Rs increase the immune activating properties of IL-6. We estimated sIL-6R serum levels in 25 schizophrenic patients and 25 healthy controls. In the patients, SIL-6R-CSF levels were also measured. The psychopathology was rated according to the AMDP system. We found a significant correlation between serum and cerebrospinal fluid (CSF) levels of sIL-6R, suggesting that serum levels may be a meaningful marker for the central action of sIL-6R. Moreover, significant correlations between the paranoid-hallucinatory syndrome and sIL-6R levels both in serum and CSF were observed. This finding suggests that IL-6 plays a role in the paranoid-hallucinatory symptomatology in schizophrenia. This can be understood regarding the influence of IL-6 to the catecholaminergic neurotransmission. The downregulating effects of neuroleptic treatment to sIL-6R demonstrate that the sIL-6R levels are decreased in the whole group of schizophrenic patients compared to controls.