title: [Intra-leukocyte cystine in cystinosis treated with cysteamine].
abstract: Data on cystine leukocyte content are analyzed in cystinotic patients receiving cysteamine as a depleting agent of cellular cystine. During 2 years, 63 measurements of cystine leucocyte content were performed in 15 cystinotic patients, aged 20 months to 22 years, taking daily 40 to 65 mg/kg of cysteamine. An original method was used to measure leukocyte cystine: a binding protein assay with a specific cystine-binding protein from E. coli. Results were taken individually because of various clinical situations in patients. In 8 patients taking cysteamine regularly, 6 hours after a dose, cystine leukocyte content was between 1 and 2 nmol 1/2 cystine/mg protein, about 10 times less than basal values without treatment and 5 to 10 times more than control subjects. In less compliant patients, cystine leukocyte content was close to basal values without treatment (3 to 25 nmol/mg). Some variability was observed between individuals receiving cysteamine: pharmacokinetic parameters may need further investigation. This sensitive and specific assay helped in controlling compliance and adjusting dosage regimen in each patient. The aim was to maintain a minimum effective dosage in order to avoid toxic side effects of cysteamine.
authors.affiliation: Service de Biochimie, Hôpital Necker Enfants Malades, Paris.
authors.forename: C
authors.initials: C
authors.lastname: Ged
authors.forename: G
authors.initials: G
authors.lastname: Jean
authors.forename: M J
authors.initials: MJ
authors.lastname: Tete
authors.forename: M
authors.initials: M
authors.lastname: Broyer
authors.forename: P
authors.initials: P
authors.lastname: Kamoun
mesh_terms: D000293:Adolescent; D000328:Adult; D001667:Binding, Competitive; D002648:Child; D002675:Child, Preschool; D003543:Cysteamine / Q000008:administration & dosage / Q000627:therapeutic use*; D003553:Cystine / Q000097:blood*; D003554:Cystinosis / Q000097:blood* / Q000188:drug therapy*; D004334:Drug Administration Schedule; D005260:Female; D006801:Humans; D007223:Infant; D007962:Leukocytes / Q000737:chemistry*; D008297:Male; D010349:Patient Compliance; D011863:Radioimmunoassay
chemical_list: D003553:Cystine; D003543:Cysteamine
vernacular_title: Cystine intra-leucocytaire dans les cystinoses traitées par la cystéamine.