MedWire News: Schizophrenia patients have significantly increased expression of alpha defensin protein in T-cell lysates and plasma, say scientists who suggest that the protein may be a blood marker for the condition.

There are no consistent pathologic features in schizophrenia, and diagnosis relies on clinical interview, which is made more difficult by a complex symptomatology that overlaps with other conditions, say Sabine Bahn, from the University of Cambridge, and colleagues. As rapid and effective treatment has been shown to have a positive impact on outcomes, the identification of schizophrenia biomarkers is of great importance.

To investigate further, the researchers profiled proteins anti-CD3 stimulated and unstimulated peripheral blood T-cell lysates from 15 minimally medicated and unmedicated schizophrenia patients and 15 age-, gender-, race-, and smoking-matched controls.

Using cation exchange chips with surface enhanced laser desorption ionization time of flight mass spectrometry, the team analyzed the presence of alpha defensins based on masses and cationic properties.

The findings, published in the journal Molecular and Cellular Proteomics, reveal that absolute quantification of alpha defensins in T-cell lysates was possible in six patients and 18 healthy controls. This demonstrated that alpha defensin levels were significantly increased in patients in comparison with controls.

Further study of plasma samples taken from 21 monozygotic twins discordant for schizophrenia and eight pairs of healthy, unaffected twin pairs showed that both affected and unaffected twins had significantly increased alpha defensin levels in comparison with controls, with unaffected twins having levels between those recorded in patients and controls.

"Our results demonstrate increased alpha defensins in the unaffected discordant twin in the absence of overt schizophrenia associated pathology," the team writes. "Thus alpha defensins appear to represent a blood marker associated with the risk of developing schizophrenia, rather than a consequence of pathology."

They continue: "Further investigation into underlying causes and consequences of increased alpha defensin expression in schizophrenia may further our understanding of pathological mechanisms in schizophrenia and may also aid in the diagnosis and monitoring of this devastating disorder."

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