Parkinson's disease (PD) is a neurodegenerative disease of the central nervous system (CNS), in which the cytokine network may be deranged, leading to an altered immunoregulation. Tumor necrosis factor(TNF)-alpha, a cytokine with pleiotropic neuroimmune effects, has specific receptors on human lymphocytes, as well as on other cell types, even in the CNS. The aim of the present study was to assay TNF-alpha binding on peripheral blood T cells from PD patients, as compared with healthy subjects. We found on T lymphocytes from parkinsonian patients significantly more TNF-alpha receptors than on those from controls (B (max): 637+/-23 vs. 131+/-6 (mean+/-S.E.M.) receptors/cell). Such TNF-alpha binding sites are of the same type in patients and healthy subjects (K(d): 66.8+/-5.1 vs. 70.7+/-5.6 (mean+/-S.E.M.) pM). These results are discussed in terms of PD immunopathogenesis, since it has been reported that activated T lymphocytes have increased amounts of TNF-alpha receptors.