title: A preliminary comparison of flow cytometry and tube agglutination assays in detecting red blood cell-associated C3d.
abstract: This study compared flow cytometric analysis with tube agglutination assays for the detection of red blood cell (RBC)-associated complement and immunoglobulins (Igs). RBCs from 20 patients with reactive tube direct antiglobulin tests (DATs) were evaluated by flow cytometry with anti-C3d, anti-IgG, anti-IgM and anti-IgA. Serial samples were also tested from a patient at risk of passenger lymphocyte haemolysis. Results of flow cytometry and tube assays for anti-IgG were as follows: 12 of 20 samples reactive in both; six of 20 nonreactive in both; two of 20 discordant with a reactive tube and a nonreactive flow cytometry assay. Anti-C3d results showed nine of 20 reactive in both and 11 of 20 discordant with a nonreactive tube and a reactive flow cytometry assay. In the IgM flow cytometry assay, three samples were reactive with anti-IgM. Samples from a group A woman who was transplanted with stem cells from a group B donor showed that on days 3 through 6 post-transplant, the flow cytometry assays for anti-IgG and/or anti-C3d were reactive, whilst the tube assays were nonreactive. In conclusion, flow cytometric analysis is more sensitive than the tube assay for the detection of RBC-associated C3d. Further studies are needed to determine the correlation of C3d levels with clinical sequelae.
authors.affiliation: Department of Transfusion Medicine, Warren G. Magnuson Clinical Center, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-1184, USA. dstroncek@mail.cc.nih.gov
authors.forename: D F
authors.initials: DF
authors.lastname: Stroncek
authors.forename: J M
authors.initials: JM
authors.lastname: Njoroge
authors.forename: J L
authors.initials: JL
authors.lastname: Procter
authors.forename: R W
authors.initials: RW
authors.lastname: Childs
authors.forename: J
authors.initials: J
authors.lastname: Miller
mesh_terms: D000328:Adult; D000743:Anemia, Hemolytic / Q000175:diagnosis; D003179:Complement C3b / Q000032:analysis / Q000276:immunology; D015933:Complement C3d / Q000032:analysis*; D003951:Diagnostic Errors; D004912:Erythrocytes / Q000276:immunology*; D005434:Flow Cytometry / Q000592:standards*; D006386:Hemagglutination Tests / Q000592:standards*; D006801:Humans; D007136:Immunoglobulins / Q000032:analysis / Q000276:immunology; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D007136:Immunoglobulins; D003179:Complement C3b; D015933:Complement C3d