Increased number of monocytes and plasma levels of MCP-1 and YKL-40 in first-episode psychosis.

OBJECTIVE: Accumulating evidence implicates immune activation in the development of schizophrenia. Here, monocyte numbers, monocyte chemoattractant protein-1 (MCP-1) and chitinase-3-like protein 1 (YKL-40) were investigated in plasma and cerebrospinal fluid (CSF) in first-episode psychosis (FEP) patients.

METHOD: CSF and blood were sampled from 42 first-episode psychosis (FEP) patients and 22 healthy controls. The levels of YKL-40 and MCP-1 were measured using electrochemiluminescence assay, and blood monocytes were counted using an XN-9000-hematology analyzer.

RESULTS: We found higher plasma levels of MCP-1 and YKL-40 in FEP patients compared with healthy controls, a condition that was unrelated to antipsychotic and/or anxiolytic medication. This was combined with an increased number of blood monocytes and a borderline significant increase in YKL-40 levels in the CSF of tobacco-free FEP patients. Plasma or CSF chemokines or blood monocytes did not correlate with the severity of symptoms or the level of functioning.

CONCLUSION: These data demonstrate activation of monocytes in FEP and strengthens the idea of an immune dysfunction of psychotic disorders. Further studies are required to perceive a role of YKL-40 and MCP-1 in the initiation and progression of schizophrenia.