Objective: Immune system abnormalities in schizophrenia have been previously studied. According to the present point of view, an infection or autoimmune process might be occurring in the form of cellular and/or humoral immune system abnormalities in schizophrenia. Furthermore, several effects of antipsychotic medication on the immunological profile of schizophrenic patients have been demonstrated. The present study aimed to compare the total T-lymphocytes level and the T-lymphocyte subset ratios in schizophrenia patients not treated with antipsychotics and healthy controls. The relationship between disease duration, symptom severity, and treatment response and T-lymphocyte profiles were investigated.

Methods: The study included 14 patients (11 antipsychotic naive, 3 antipsychotic free for at least 6 months) diagnosed with schizophrenia or schizophreniform disorder that were compared to age- and sex-matched healthy controls in terms of the total T-lymphocytes level and T-lymphocyte subset ratios using flow-cytometry. The relationship of the T-lymphocyte profiles, to disease duration and treatment response was investigated.

Results: The groups were not different in terms of total T-lymphocytes level and T-lymphocyte subset ratios; however, the antipsychotic naive patients and the group with disease duration < 2 years had lower rates of T8-lymphocytes. Total T-lymphocytes and the T8-lymphocyte ratio increased after treatment. Clinical improvement was correlated with total T-lymphocytes and the T4-lymphocyte subset ratio.

Conclusion: Cellular immune system abnormalities in schizophrenia may be intrinsic factors. Changes in the cellular immune system are associated with treatment response and might be candidates for biological markers.