title: Sandwich ELISA for hemoglobin A2 quantification and identification of beta-thalassemia carriers.
abstract: Hemoglobin (Hb) A2 (alpha2delta2) is a minor hemoglobin in human red blood cells. An abnormal increase in the level of HbA2 is the most significant parameter in the diagnosis of beta-thalassemia carriers. In this study, we produced two monoclonal antibodies (mAbs) that specifically react to the delta-globin chain of HbA2. A sandwich type ELISA was developed employing the produced anti-HbA2 mAbs. HbA2 levels quantified by the developed sandwich ELISA were highly correlated with those obtained from the standard HPLC method (r = 0.934, p < 0.001). HbA2 levels determined by the ELISA were 4.4 +/- 1.9% in beta-thalassemia heterozygotes compared to 1.4 +/- 0.8, 1.9 +/- 0.8, 1.5 +/- 0.8 and 1.5 +/- 0.6% in normal subjects, HbE heterozygotes, suspected alpha-thalassemia heterozygotes and HbE homozygotes, respectively. Using a cut-off value of 2.5%, beta-thalassemia heterozygotes could be separated from non-beta-thalassemia heterozygotes with the same accuracy as obtained using the standard HPLC method. More importantly, the developed ELISA was able to determine HbA2 levels in HbE-bearing individuals which could not be done by the HPLC method. Our results suggest that this sandwich ELISA can be applied for mass screening for beta-thalassemia heterozygotes, especially in resource-limited countries, where beta-thalassemia is highly prevalent.
authors.affiliation: Division of Clinical Immunology, Department of Medical Technology, Faculty of Associated Medical Sciences, Chiang Mai University, Chiang Mai 50200, Thailand.
authors.forename: Surakit
authors.initials: S
authors.lastname: Kuntaruk
authors.forename: Thanusak
authors.initials: T
authors.lastname: Tatu
authors.forename: Tiemjan
authors.initials: T
authors.lastname: Keowkarnkah
authors.forename: Watchara
authors.initials: W
authors.lastname: Kasinrerk
mesh_terms: D000328:Adult; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology*; D000918:Antibody Specificity; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods* / Q000592:standards; D006443:Hemoglobin A2 / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D006446:Hemoglobin E / Q000276:immunology / Q000378:metabolism; D006579:Heterozygote; D006720:Homozygote; D006801:Humans; D007114:Immunization; D008403:Mass Screening / Q000379:methods / Q000592:standards; D051379:Mice; D008807:Mice, Inbred BALB C; D015203:Reproducibility of Results; D017085:alpha-Thalassemia / Q000097:blood / Q000175:diagnosis; D017086:beta-Thalassemia / Q000097:blood* / Q000175:diagnosis*
chemical_list: D000911:Antibodies, Monoclonal; D006443:Hemoglobin A2; D006446:Hemoglobin E