title: Antiglobulin testing for CR1-related (Knops/McCoy/Swain-Langley/York) blood group antigens: negative and weak reactions are caused by variable expression of CR1.
abstract: The Knops, McCoy, Swain-Langley and York antigens have recently been identified as being on complement receptor type 1 (CR1, CD35, C3b/C4b receptor). We examined the relationship between CR1 expression and the reactivity of the CR1-related blood group antigens with their specific antibodies. RBC from donors of selected phenotypes were tested by hemagglutination using two monoclonal antibodies to CR1, as well as anti-Kna, -McCa, -S1a, -'Kn/McC' and -Yka. Monoclonal antibodies 3D9 and E11 required approximately 250 and approximately 400 CR1/RBC to obtain a positive reaction. Agglutination of antigen-positive cells by human polyclonal antisera was related to the CR1/RBC: thus, cells expressing 20-100 CR1/RBC were negative and included the previously designated null phenotypes for this collection, 100-150 were weak or negative, and greater than 200 were usually positive. One RBC sample carried Yka on the 190,000 dalton (A or F allele), but not the 220,000 dalton (B or S allele) variant of CR1, and gave inconsistent reactions with Yka antisera. These data provide an explanation for certain of the serologic characteristics of the CR1-related blood group antigen system.
authors.affiliation: Howard Hughes Medical Institute Laboratories, Department of Medicine, Washington University School of Medicine, St. Louis, Mo.
authors.forename: J M
authors.initials: JM
authors.lastname: Moulds
authors.forename: J J
authors.initials: JJ
authors.lastname: Moulds
authors.forename: M
authors.initials: M
authors.lastname: Brown
authors.forename: J P
authors.initials: JP
authors.lastname: Atkinson
mesh_terms: D000483:Alleles; D000911:Antibodies, Monoclonal / Q000276:immunology; D016477:Artifacts; D001789:Blood Group Antigens / Q000235:genetics / Q000276:immunology*; D003298:Coombs Test; D000939:Epitopes / Q000276:immunology; D004910:Erythrocyte Membrane / Q000276:immunology*; D005188:False Negative Reactions; D015870:Gene Expression; D006801:Humans; D007118:Immunoassay; D010641:Phenotype; D012150:Polymorphism, Restriction Fragment Length; D011951:Receptors, Complement / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology*; D017463:Receptors, Complement 3b
chemical_list: D000911:Antibodies, Monoclonal; D001789:Blood Group Antigens; D000939:Epitopes; D011951:Receptors, Complement; D017463:Receptors, Complement 3b