title: Peripheral catabolism of CR1 (the C3b receptor, CD35) on erythrocytes from healthy individuals and patients with systemic lupus erythematosus (SLE).
abstract: The present study investigated the rate of catabolism of CR1 (the C3b receptor, CD35) on erythrocytes (E) in vivo, in relationship with the expressed number of CR1/E, the CR1.1 HindIII quantitative CR1 polymorphism, and cell age. The relationship between the number of CR1/E and cell age was analysed by measuring G6PDH activity in E that had been sorted according to high or low expression of CR1 (CD35), by assessing the expression of CR1 (CD35) on E separated according to cell density, and by comparing the number of CR1 (CD35) antigenic sites on reticulocytes and on E. A physiological catabolism of CR1 (CD35) manifested by a reduction in the number of CR1 (CD35) antigenic sites/E with cell ageing was consistently observed in healthy individuals. The number of CR1/E decreased with ageing of E according to a complex pattern that associated an exponential decay and an offset. Calculated half-lives of CR1 (CD35) ranged between 11 and 32 days in healthy individuals. A more rapid loss of CR1 (CD35) with cell ageing occurred on cells from individuals expressing high numbers of CR1/E. In patients with systemic lupus erythematosus (SLE), half-lives of CR1 (CD35) on E were in the same range as those of healthy individuals with a similar quantitative CR1 genotype; the number of CR1 (CD35) on reticulocytes was reduced and linearly related to the number of CR1/E, independently of the patients' quantitative CR1 genotype. Transfusion experiments with E bearing high or low amounts of CR1/E indicated the lack of preferential removal of E bearing high numbers of CR1 (CD35) in patients with SLE. These results indicate that the rate of loss of CR1 (CD35) from E with cell ageing is directly related to the quantitative CR1 phenotype and suggest that enhanced peripheral catabolism is not the sole mechanism of the acquired loss of CR1 (CD35) on E in patients with SLE.
authors.affiliation: Laboratoire d'Immunologie, CHU Robert Debré, Reims, France.
authors.forename: J H
authors.initials: JH
authors.lastname: Cohen
authors.forename: H U
authors.initials: HU
authors.lastname: Lutz
authors.forename: J L
authors.initials: JL
authors.lastname: Pennaforte
authors.forename: A
authors.initials: A
authors.lastname: Bouchard
authors.forename: M D
authors.initials: MD
authors.lastname: Kazatchkine
mesh_terms: D015703:Antigens, CD / Q000378:metabolism; D002452:Cell Count; D002469:Cell Separation; D003179:Complement C3b / Q000378:metabolism*; D004912:Erythrocytes / Q000378:metabolism*; D005434:Flow Cytometry; D005954:Glucosephosphate Dehydrogenase / Q000378:metabolism; D006207:Half-Life; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000378:metabolism*; D011951:Receptors, Complement / Q000378:metabolism*; D017463:Receptors, Complement 3b
chemical_list: D015703:Antigens, CD; D011951:Receptors, Complement; D017463:Receptors, Complement 3b; D003179:Complement C3b; D005954:Glucosephosphate Dehydrogenase