Ganguli and colleagues,1 in the August 1995 issue of the ARCHIVES, provide convincing evidence that phytohemagglutinin-induced in vitro interleukin-2 (IL-2) production is reduced in patients with schizophrenia who have never received medication compared with healthy control subjects. They note that decreased IL-2 secretion and increased systemic levels of soluble IL-2 receptors (sIL-2Rs) are robust findings that signify an alteration of immunologic functions in patients with schizophrenia. Documentation of altered IL-2 secretion in drug-naive patients is important because antipsychotic medication can influence the IL-2/IL-2 receptor system as demonstrated by clozapine-induced increases in plasma sIL-2R levels.2
In addition to antipsychotic medication, smoking may affect the immune system of patients with schizophrenia. In healthy smokers, phytohemagglutinininduced lymphocyte proliferation was shown to be suppressed,3 and systemic sIL-2R levels were reported to be increased.4,5 The prevalence of smoking is high in patients with schizophrenia,6 but neither the study by Ganguli