title: Rabbit IgG antibodies against cord red blood cell membranes bind to complement receptor 1 (CD35).
abstract: We have previously shown that a subpopulation of cord/fetal red blood cells (RBC) binds rabbit IgG antibodies raised against cord RBC and absorbed on adult RBC (F-IgG), while control IgG, raised against and absorbed on adult RBC (A-IgG), fails to do so. In the present study, F-IgG maintained its binding to cord RBC surface antigens following absorption on spectrin but not after absorption on skeleton-stripped RBC membranes. Spectrin-absorbed F-IgG- but not A-IgG-affinity-purified material from cord RBC contained polypeptides with apparent MW of complement receptor 1 (CR1) allotypes. Moreover, on immunoblotting these polypeptides reacted with 125I-F-IgG as well as with 125I-anti-CR1 mAb, and binding of 125I-anti-CR1 mAb was inhibited by unlabelled F-IgG. In addition, cord RBC incubated with F-IgG prior to reaction with anti-CR1 showed decreased fluorescence intensity on flow cytometry. Taken together the results suggest that F-IgG binds to CR1 which shows increased expression/accessibility on a subpopulation of cord/fetal RBC.
authors.affiliation: Dipartimento di Medicina Sperimentale e Diagnostica, Sezione di Patologia Generale, Università di Ferrara, Italy.gla@ifeuniv.unife.it
authors.forename: A L
authors.initials: AL
authors.lastname: Giuliani
authors.forename: R
authors.initials: R
authors.lastname: Pora
authors.forename: M
authors.initials: M
authors.lastname: Verenini
authors.forename: L
authors.initials: L
authors.lastname: Unis
authors.forename: G
authors.initials: G
authors.lastname: Graldi
authors.forename: L
authors.initials: L
authors.lastname: Ferrari
authors.forename: F
authors.initials: F
authors.lastname: Lanza
authors.forename: E
authors.initials: E
authors.lastname: Wiener
authors.forename: H U
authors.initials: HU
authors.lastname: Lutz
authors.forename: F
authors.initials: F
authors.lastname: Vesce
authors.forename: G
authors.initials: G
authors.lastname: Berti
mesh_terms: D000818:Animals; D001667:Binding, Competitive; D004591:Electrophoresis, Polyacrylamide Gel; D004912:Erythrocytes / Q000276:immunology* / Q000378:metabolism; D005312:Fetal Blood / Q000276:immunology* / Q000378:metabolism; D005434:Flow Cytometry; D006801:Humans; D015151:Immunoblotting; D007074:Immunoglobulin G / Q000276:immunology* / Q000378:metabolism; D011817:Rabbits; D017463:Receptors, Complement 3b / Q000276:immunology* / Q000378:metabolism
chemical_list: D007074:Immunoglobulin G; D017463:Receptors, Complement 3b