Drug-related autoimmune hemolytic anemia appearing with warm-reacting antibodies can be classified according to the offending substances. One of the subtypes can be induced by alpha-methyldopa. However, the pathophysiology of the underlying mechanism is not yet known. In parallel, patients with Parkinson's disease and other extrapyramidal disorders, who are under administration of dopaminergic drugs, often present with abnormal findings with respect to immune parameters. In order to reveal further mechanisms within the immune response, the capability of patients under dopaminergic medication to release cytokines after a stimulatory signal was examined. Therefore, 18 patients who were treated with the dopamine analogue lisuride were compared with an aged-matched control group of 21 healthy volunteers. After stimulation with phytohemagglutinin (PHA), mitogen-induced concentrations of interferon-gamma were significantly higher in the patients treated with lisuride than in the control group. Interferon-gamma leads to an upregulation of MHC class-I and especially class-II molecules on antigen-presenting cells and to an induction of antibody production in B cells. This condition can result in the induction of an autoimmune process. It might be supposed that alpha-methyldopa-type autoimmune hemolytic anemia is mediated by elevated levels of interferon-gamma produced in T cells after a stimulatory signal.