Immunologic alterations in schizophrenia: Neopterin, L-kynurenine, tryptophan and T-cell subsets in the acute stage of illness

Abstract

It is well established now that in diseases with activated cell-mediated immunity increased formation of neopterin and degradation of tryptophan is an indication of endogenous production of interferon-γ in patients. Therefore increased neopterin levels are associated with increased kynurenine levels and decreased tryptophan in patients suffering from virus infections, malignant diseases or autoimmunity. To investigate cell-mediated immunity in schizophrenia, neopterin, L-kynurenine, L-tryptophan and T-cell-subsets were measured in 10 chronic schizophrenic patients, addmitted to hospital due to acute psychiatric relapse. Low neopterin concentrations were found at the beginning of hospitalisation and followed by a significant increase at the time of discharge (p = 0.02). Mean neopterin values were still within the 95th percentile of healthy controls. Kynurenine levels showed a similar development (p = 0.03) as neopterin whereas tryptophan values were low at admission without any significant changes thereafter. CD3+ and CD4+-cells presented with highest numbers at admission, followed by a continuous decrease and NK-cells were found lowest on day 0 with a gradual increase by day 7. These findings argue against acute virus infection in acutely ill schizophrenic patients because this would be associated with incerased neopterin fromation and tryptophan dagradation, rather the data would be in line with a shift from TH-1 to TH-2-type immune reaction which which is common in chronic infections.