title: Discrepancies in reverse ABO typing due to prozone. How safe is the immediate-spin crossmatch?
abstract: Three group O sera manifesting prozone in reverse ABO tests are reported. All were implicated in erroneous blood typing results. One sample failed to react with A1 red cells (RBCs) in immediate-spin (IS) tests, had anti-A and -B titers of 8192 and 2048, respectively, by indirect antiglobulin technique (IAT), and was from a diabetic patient; the parenteral administration of A substance present in porcine insulin is a possible cause of hyperimmunity in this case. The second sample was from the recipient of a single unit of group B fresh-frozen plasma; the serum anti-A and -B titers were 10,240 by IAT, but only weak reactions with A1 and B RBCs were noted in routine IS reverse typing tests; the hyperimmunity in the patient concerned was likely due to crossreacting anti-A, B stimulated by B-active glycoproteins and/or glycolipids in the transfused plasma. The third serum also had anti-A and anti-B IAT titers of 10,240 but did not react with A1 and B RBCs by IS; the hyperimmunity in this case may be related to sepsis from intestinal flora carrying A- and/or B-like antigens. These antibodies lysed A1 and/or B RBCs in tests incubated at room temperature (RT) and strongly agglutinated those RBCs by IS when diluted 10-fold with saline. The absence of the prozone phenomenon in tests with RBCs suspended in diluents containing EDTA is consistent with the previously published mechanism for anti-A prozone: namely, the steric hindrance of agglutination by the C1 component of human complement.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Pathology, University of Michigan Medical Center, Ann Arbor.
authors.forename: W J
authors.initials: WJ
authors.lastname: Judd
authors.forename: E A
authors.initials: EA
authors.lastname: Steiner
authors.forename: D B
authors.initials: DB
authors.lastname: O'Donnell
authors.forename: H A
authors.initials: HA
authors.lastname: Oberman
mesh_terms: D000017:ABO Blood-Group System; D000328:Adult; D000368:Aged; D001788:Blood Grouping and Crossmatching / Q000379:methods*; D003298:Coombs Test; D005188:False Negative Reactions; D005260:Female; D006801:Humans; D007518:Isoantibodies / Q000032:analysis; D008875:Middle Aged
chemical_list: D000017:ABO Blood-Group System; D007518:Isoantibodies