title: Presence of the C3b complement receptor (CR1) antigen in the glomerular basement membrane of human fetal kidneys.
abstract: The distribution pattern of the C3b receptor (CR1) antigen, one of the earliest differentiation markers of the podocyte plasma membrane, has been studied during human renal ontogenesis by indirect immunofluorescence and immunoelectronmicroscopy using Fab'2 fragments of anti-CR1 antibodies. CR1 antigen has been detected at the open-stage glomerulus, which precedes constriction of the vascular pole, along the capillary wall, in a thick and homogeneous pattern of staining. By immunoelectronmicroscopy, CR1 antigen was present on the porocyte plasma membrane towards the glomerular basement membrane (GBM), and diffusely distributed within the GBM according to a decreasing intensity gradient from podocytes to endothelial cells. At a later stage of differentiation ('closed' glomerulus stage) when constriction of the vascular pole has occurred, the podocyte plasma membrane appeared diffusely labelled for CR1; the GBM was also stained with a decreasing intensity gradient from podocytes to endothelial cells. This result indicates that a plasma membrane receptor belonging to the cell coat of podocytes can be found in the extracellular space within the GBM. Thus the antigenic repertoire of the GBM of human fetal kidney comprises antigens of constituent molecules of the extracellular matrix and planted antigens originating from adjacent cells.
authors.affiliation: INSERM U28, Hôpital Broussais, Paris, France.
authors.forename: M D
authors.initials: MD
authors.lastname: Appay
authors.forename: M D
authors.initials: MD
authors.lastname: Kazatchkine
authors.forename: F
authors.initials: F
authors.lastname: Mounier
authors.forename: J
authors.initials: J
authors.lastname: Bariety
mesh_terms: D001485:Basement Membrane / Q000032:analysis / Q000648:ultrastructure; D005110:Extracellular Space / Q000032:analysis; D005333:Fetus / Q000032:analysis* / Q000648:ultrastructure; D005455:Fluorescent Antibody Technique; D006801:Humans; D007678:Kidney Glomerulus / Q000032:analysis* / Q000648:ultrastructure; D011951:Receptors, Complement / Q000032:analysis*; D017463:Receptors, Complement 3b
chemical_list: D011951:Receptors, Complement; D017463:Receptors, Complement 3b