Leukocyte Elastase and Autoantibodies to Nerve Growth Factor in the Acute Phase of Schizophrenia and their Relationship to Symptomatology

Summary Many investigations suggest that abnormalities of the immune system are involved in the pathophysiology of schizophrenia. We recently found increased activity of leukocyte elastase (LE) and elevated levels of autoantibodies to neurospecific protein-nerve growth factor (Aab to NGF)-products of the innate and adaptive arms of the immune system in the serum of patients with acute stage schizophrenia. The aim of this study is to elucidate whether or not the changes of LE activity and Aab to NGF level are related to prominent features of schizophrenia. Patients (n=71) corresponding to ICD-10 criteria for relapseremitting schizophrenia were assessed by the Positive and Negative Syndrome Scale (PANSS). Patients with predominantly positive symptoms showed significantly elevated serum levels of Aab to NGF compared to patients with predominantly negative symptoms, who were more likely to exhibit the high LE activity. Moreover, progression of positive symptoms was coupled with gradual increase of Aab to NGF level and reduction of LE activity. Based on these findings we conclude that the high levels of Aab to NGF relate to a clinical picture characterised mainly by positive symptoms of schizophrenia, whereas high LE-activities relate to a clinical picture with mainly negative symptoms of schizophrenia.