Circulating plasma factors in Parkinson's disease enhance nitric oxide release of normal human neutrophils

Nitric oxide (-NO)-mediated toxicity has been involved in neurodegenerative diseases, including Parkinson's disease (PD). We have recently reported an increase of about 50% in -NO production rate in PMA-activated polymorphonu clear leukocytes (PMN) from either newly diagnosed or chronically heated PD patients. As humoral factors in sera from PD patients could inhibit cell d opaminergic activity, the aim of this study was to determine whether a plas ma circulating factor from PD patients could modify -NO metabolism in PMN f rom healthy control subjects. To this purpose, we determined simultaneously the maximal production rate of -NO and hydrogen peroxide (H2O2) of PMA-act ivated PMN isolated from healthy control subjects in the presence of aliquo ts of plasma of PD patients. The results showed that, after 30 min incubati on, plasma from newly diagnosed (n=4) or from L-Dopa chronically heated (n= 7) PD patients enhanced -NO release in neutrophils isolated from healthy co ntrols by about 50% and 47% respectively, with respect to non-parkinsonian control plasma (n=10); in the same condition, H2O2 production did not diffe r among the groups. These data suggest that an overproduction of -NO relate d to plasma circulating factors, already detected at initial stages of the disease, participates in the pathophysiology of Parkinson's disease. (C) 19 99 Elsevier Science B.V. All rights reserved.