Defective production of interleukin-2 in patients with idiopathic Parkinson's disease

The pathogenesis of Parkinson's disease (PD) is largely unknown. Recently, several studies have presented evidence of an immunological dysfunction in patients suffering from PD. We studied the immune responsiveness of patients with idiopathic PD (n = 20) by investigation of the ability of peripheral blood mononuclear cells to produce cytokines after mitogenic stimulation in a whole blood assay. A group of age-related healthy blood donors served as control (n = 19). Additionally, white blood count, leukocyte differentiation and lymphocyte subtyping were performed. PD patients had a significantly higher neutrophil count, but analysis of T-cell subsets showed no difference between the two groups. In peripheral blood, secretion of interleukin-2 (IL-2) after mitogenic stimulation was significantly diminished in the patients' group (p < 0.01), whereas values of IFN-alpha 2, IL-6, IFN-gamma and sIL-2R were comparable in both groups. IL-2 production correlated negatively with the mean annual dose of levodopa treatment and correlated significantly (p < 0.002) with amantadine uptake. Analysis of sex, age, duration of illness and other drug intake revealed no correlation with cytokine release. Our findings support the view that there is a selective abnormality in the immune repertoire of peripheral blood lymphocytes in patients suffering from PD, the reasons for which need to be explored.