Is T ‐helper type 2 shift schizophrenia‐specific? Primary results from a comparison of related psychiatric disorders and healthy controls

Aim An imbalance between T ‐helper type 1 ( T h1) and type 2 ( T h2) cytokines has been implicated in schizophrenia, although empirical evidence is rare. The aim of this study was to examine if a T h1/ T h2 imbalance occurs in schizophrenia and schizophrenia‐related disorder. Methods Twenty‐six subjects with schizophrenia, 26 subjects with schizophrenia‐related disorders, and 26 healthy controls were recruited. The Human T h1/ T h2 Cytokine Cytometric Bead Array Kit‐ II was utilized to assess serum T h1/ T h2 cytokines and ratios simultaneously. MANOVA was used to detect differences among the three diagnostic groups in distinct T h1/ T h2 cytokines/ratios. Pearson/Spearman correlations were used to examine the relationships between distinct T h1/ T h2 cytokines/ratios and clinical/psychopathological data in schizophrenia. Results Interferon ( IFN) ‐γ/interleukin ( IL) ‐4, IFN ‐γ/ IL ‐10, IL ‐2/ IL ‐4, and tumor necrosis factor ( TNF) ‐α/ IL ‐4 ratios were significantly decreased in schizophrenia, but not in schizophrenia‐related disorders compared to healthy controls. IFN ‐γ/ IL ‐4 and IFN ‐γ/ IL ‐10 in schizophrenia subjects positively correlated with age, but not in schizophrenia‐related disorder subjects or in healthy controls. Conclusion A clear T h2 shift was observed in schizophrenia, but not in schizophrenia‐related disorders. The T h2 shift in schizophrenia appeared to be an aberrant developmental phenomenon.