title: Enumeration of CR1 complement receptors on erythrocytes using a new method for detecting low density cell surface antigens by flow cytometry.
abstract: A sensitive enhancing system was developed for detecting low density cell surface antigen by flow cytometry. The system termed the 'super avidin-biotin system' (SABS) uses biotinylated antibody, phycoerythrin-streptavidin (StreptA-PE), biotinylated goat anti-streptavidin antibody, and StreptA-PE. CR1 complement receptor antigenic sites were quantified on erythrocytes from healthy individuals and patients with antibodies against human immunodeficiency virus (HIV) using SABS and a conventional radioimmunoassay (RIA) with monoclonal anti-CR1 antibody. As little as 50 sites/cell were detected using either SABS or RIA. Accurate quantification of CR1 antigenic sites was achieved within the range of 100-1300 sites/cell. Similar results were obtained using either of the two methods. Intra-assay and day-to-day reproducibilities using SABS were 2% and 12% respectively, comparable to those of conventional RIA measurements. In addition to enumeration of CR1 on erythrocytes for clinical purposes, the use of SABS may probably be extended to a wide number of situations where a sensitive detection of low density cell surface antigen is needed.
mesh_terms: D000163:Acquired Immunodeficiency Syndrome / Q000097:blood; D000911:Antibodies, Monoclonal; D000954:Antigens, Surface / Q000032:analysis*; D001360:Avidin; D001665:Binding Sites; D001710:Biotin; D002469:Cell Separation; D004912:Erythrocytes / Q000648:ultrastructure*; D005434:Flow Cytometry / Q000379:methods*; D006801:Humans; D011863:Radioimmunoassay / Q000379:methods; D011951:Receptors, Complement / Q000032:analysis*; D017463:Receptors, Complement 3b
chemical_list: D000911:Antibodies, Monoclonal; D000954:Antigens, Surface; D011951:Receptors, Complement; D017463:Receptors, Complement 3b; D001360:Avidin; D001710:Biotin