Détermination de l'activité enzyme de conversion de l'angiotensine I dans le liquide céphalorachidien pour le diagnostic de la neurosarcoïdose

Sarcoidosis is a disease of unknown aetiology. This granulomatous disease is essentially localized in lung and skin, but many other localizations are possible, such as in nervous system. Sometimes the neurological involvement is alone leading to a differential diagnosis from other neurological diseases. Angiotensin I-converting enzyme (ACE) is synthesized by sarcoidotic granulomas and diffuses in various biological fluids. The determination of ACE activity in cerebrospinal fluid (CSF) can help for the diagnosis of neurosarcoidosis, associated or not to its determination in plasma. We developed a radiometric assay for the determination of ACE activity in CSF since the methods for plasma cannot be used because ACE activity is low in CSF, as well as in pathological situations. At the analytical point of view this assay is sensitive, specific and reproducible. We established a normal range and yielded recommendations to give the results, particularly in function of the aspect of the CSF and the proteinorrachia. But increased level of ACE in CSF is not specific of neurosarcoidosis since elevations were also shown in meningitis. We can claim for the routine use of ACE assay in CSF for differential diagnosis by eliminating neurosarcoidosis, as well as for positive diagnosis of this disease, but in both cases with the confrontation to other parameters.