[Dopaminergic receptors on lymphocytes in idiopathic Parkinson's disease (author's transl)]

(3H) spiroperidol binding has been measured in lymphocytes from patients with Parkinson's disease and age matched healthy volunteers. A dramatic decrease (73 p. 100) in the number of binding sites Bmax without any variation of the affinity KD has been observed in untreated Parkinsonian patients. This decrease in Bmax is linearly correlated with the degree of disability of the Parkinsonian patients (r = 0.891, p less than 0.001). This decrease appeared to be relatively selective since no variation was observed with patients suffering of other neurological disorders. The possible relationships with the number of striatal dopamine receptors are discussed. With levodopa therapy, Bmax had the same mean value as in control subjects. This result means that levodopa induces an increase in lymphocyte binding sites and in five patients this increase could be observed by study before and during drug administration. In some severely disabled patients who had received levodopa for several years, Bmax was found much lower or higher than the mean value, which may suggest different interpretations of drug unefficiency.