Cytokine serum levels, autologous mixed lymphocyte reaction and surface marker analysis in never medicated and chronically medicated schizophrenic patients

A number of immunological parameters were studied in 82 DSM-III-R diagnosed schizophrenic patients (53 first drug-naive and 29 medicated chronic patients) as well as 67 healthy blood donors. The serum levels of interleukin-2 (IL-2), interleukin-1 beta (IL-1 beta) and tumour necrosis factor-alpha (TNF-alpha) were measured and correlated with cellular immunity, as assessed by the autologous mixed lymphocyte reaction (AMLR). T lymphocyte subsets were also examined. The above immune parameters were reassessed in a subgroup of ii first-episode, drug-naive patients 1 month after neuroleptic medication. IL-2 serum levels were significantly lower, and IL-1 beta and TNF-alpha were significantly higher in schizophrenic patients compared with healthy donors (P<0.001), no significant difference was observed between the two patient groups (medicated and not medicated). Abnormal cytokine serum levels were associated with decreased AMLR responses in vitro. Increased percentages of activated CD4+ and CD16+ natural killer cells, as well as cells expressing ICAM-1 adhesion molecules and IL-2 specific receptors, were detected in the patients. Immunophenotype studies revealed a higher percentage of cells expressing IL-2 receptors in medicated chronic schizophrenic patients compared with drug-naive patients. The abnormal cytokine production in vivo. along with the low AMLR responses in vitro. and the high percentage of activated CD4+ lymphocytes presented in this study suggest alterations in the immune system of schizophrenic patients (medicated or not medicated) consistent with immune activation. (C) 2001 Elsevier Science B.V. All rights reserved.