Inter-laboratory Variability of Anti-β2-glycoprotein I Measurement

Guido Reber; Inger Schousboe; Angela Tincani; Marielle Sanmarco; Tanja Kveder; Philippe de Moerloose; Marie-Claire Boffa; Josiane Arvieux

doi:10.1055/s-0037-1613156

Thrombosis and Haemostasis, Table of Contents

Thromb Haemost 2002; 88(01): 66-73
DOI: 10.1055/s-0037-1613156

Review Article

Schattauer GmbH

Inter-laboratory Variability of Anti-β₂-glycoprotein I Measurement

A Collaborative Study in the Frame of the European Forum on Antiphospholipid Antibodies Standardization Group

Authors

Guido Reber

¹Haemostasis Unit, Geneva University Hospital, Switzerland
Inger Schousboe

²The Panum Institute, Copenhagen, Denmark
Angela Tincani

³Clinical Immunology Unit, Brescia Hospital, Italy
Marielle Sanmarco

⁴Laboratoire d’Immunologie, Hôpital de la Conception, Marseille, France
Tanja Kveder

⁵University Medical Center, Ljubljana, Slovenia
Philippe de Moerloose

¹Haemostasis Unit, Geneva University Hospital, Switzerland
Marie-Claire Boffa

⁶Department of Internal Medicine JC Piette, Hôpital de la Pitié, Paris, France
Josiane Arvieux

⁷Laboratoire d’Immunologie, CHU de Brest, France

Abstract

Summary

Inter-laboratory variability of anti-β₂-glycoprotein I antibody measurements (IgG and IgM) was investigated in the frame of the European Forum on Antiphospholipid Antibodies and its Standardization Group. Twenty-eight samples from patients with autoimmune diseases, two samples from blood donors and a set of six calibrators obtained by dilution with normal plasma of a pool of patient samples were sent to 21 European centers. Six of them used commercial kits and the others home-made assays. Marked differences in the steepness of the calibration curves obtained with the calibrator provided were observed. The standard deviations of sample measurement were high. Cut-off of positivity varied from 7 to 90 Forum Units (FU) for IgG and from 10 to 138 FU for IgM, whereas the rate of positivity varied from 50 to 93% for IgG and from 13 to 70% for IgM. No clear relationship between cut-off values and positivity rate could be established for either isotype. Adopting a common cut-off did not markedly improve the overall agreement between centers in positive/negative sample classification. Because of the majority of low positive samples, excellent concordance between centers (as defined by kappa values from 0.8 and 1) occurred only in 13% of cases for IgG and in 6% of cases for IgM, because many selected samples were low-positive. Despite the large variability of anti-β₂-glycoprotein I measurements between centers, the agreement on results with highand medium-positive samples was good.

Keywords

Anti-β₂-glycoprotein I antibodies - assays - standardization

Full Text

References

References
1 McNeil HP, Simpson RJ, Chesterman CN, Krilis SA. Anti-phospholipid antibodies are directed against a complex antigen that includes a lipidbinding inhibitor of coagulation: β₂-glycoprotein I (apolipoprotein H). Proc Natl Acad Sci USA 1990; 87: 4120-4.
2 Galli M, Comfurius P, Maasen C, Hemker HC, de Baets MH, van BredaVriesman PJC, Barbui T, Zwaal RFA, Bevers EM. Anticardiolipin antibodies (ACA) directed not to cardiolipin but to a plasma protein cofactor. Lancet 1990; 335: 1544-7.
3 Loizou S, McCrea JD, Rudje AC, Reynolds R, Boyle CC, Harris EN. Measurement of anticardiolipin antibodies by an enzyme-linked immonosorbent assay (ELISA): standardization and quantitation of the results. Clin Exp Immunol 1985; 62: 738-45.
4 Harris EN. The second international anti-cardiolipin standardization workshop/The Kingston anti-phospholipid antibody (KAPS) study group. Am J Clin Pathol 1990; 94: 476-84.
5 Harris EN, Pierangeli S, Birch D. Anticardiolipin wet workshop report. Fifth International Symposium on Antiphospholipid Antibodies. Am J Clin Pathol 1994; 101: 616-24.
6 Coulam CB, MnIntyre JA, Wagenknecht D, Rote N. Interlaboratory inconsistencies in detection of anticardiolipin antibodies. Lancet 1990; 335: 865 (Letter).
7 Reber G, Arvieux J, Comby E, Degenne D, de Moerloose P, Sanmarco M, Potron G. Multicenter evaluation of nine commercial kits for the quantitation of anticardiolipin antibodies. Thromb Haemost 1995; 73: 444-52.
8 Tincani A, Allegri F, Sanmarco M, Cinquini M, Taglietti M, Balestrieri G, Koike T, Ichikawa K, Meroni P, Boffa MC. Anticardiolipin antibody assay: a methodological analysis for a better consensus in routine determinations. A cooperative project of the European Antiphospholipid Forum. Thromb Haemost 2001; 86: 575-83.
9 Arvieux J, Roussel B, Jacob MC, Colomb MG. Measurement of antiphospholipid antibodies by ELISA using β₂-glycoprotein I as an antigen. J Immunol Methods 1991; 143: 223-9.
10 Matsuura E, Igarashi Y, Yasuda T, Triplett DA, Koike T. Anticardiolipin antibodies recognize β₂-glycoprotein I structure altered by interacting with an oxygen modified solid phase surface. J Exp Med 1994; 179: 457-62.
11 Roubey RA, Eisenberg RA, Harper MF, Winfield JB. Anticardiolipin autoantibodies recognize β₂-glycoprotein I in the absence of phospholipids. Importance of antigen density and bivalent binding. J Immunol 1995; 154: 954-60.
12 Tsutsumi A, Ichikawa K, Matsuura E, Sawada K-I, Koike T. Heterogeneous behavior of anti-β₂-glycoprotein I antibodies on various commercially available enzyme immunoassay plates coated with β₂-glycoprotein I. J Rheumatol 2000; 27: 391-6.
13 Wei TQ, Bermes EW, Jandreski AA. Antibodies against β₂-glycoprotein I and anti-cardiolipin calibrators. Clin Chem 1996; 42: 642-3.
14 Erickson EN, Najmey SS, Keil LB, El-Kadi HS, De Bari VA. Reference calibrators for IgG antibodies to β₂-glycoprotein I: preparation, properties and availability to investigators. Clin Chem 1996; 42: 1116-7.
15 Ichikawa K, Tsutsumi A, Atsumi T, Matsuura E, Kobayashi S, Hughes GRV, Khamashta MA, Koike T. A chimeric antibody with the human γ1 constant region as a putative standard for assays to detect IgG β₂-glycoprotein I-dependent anticardiolipin and anti-β₂-glycoprotein I antibodies. Arthritis Rheum 1999; 42: 2461-70.
16 Cucnik S, Ambrozic A, Bozic B, Skitek S, Kveder T. Anti-β₂-glycoprotein I ELISA: methodology, determination of cut-off values in 434 healthy Caucasians and evaluation of monoclonal antibodies as possible international standards. Clin Chem Lab Med 2000; 38: 777-83.
17 Cohen J. A coefficient of agreement for nominal scales. Educ Psych Meas 1960; 20: 37-46.
18 Bouma B, de Groot PG, van den Elsen JMH, Ravelli RBG, Schouten A, Simmelink MJA, Derksen RHWM, Kroon J, Gros P. Adhesion mechanism of human β₂-glycoprotein I to phospholipids based on its crystal structure. EMBO J 1999; 18: 5166-74.
19 Wagenknecht DR, McIntyre JA. Changes in β₂-glycoprotein I antigenicity induced by phospholipid binding. Thromb Haemost 1993; 69: 361-5.
20 Regnault V, de Maistre E, Wahl D, Lecompte T. Monovalent binding of autoantibodies to β₂-glycoprotein I, detected using surface plasmon resonance at low antigen density. Br J Haematol 2000; 109: 187-94.
21 Arvieux J, Regnault V, Hachulla E, Darnige L, Roussel B, Bensa JC. Heterogeneity and immunochemical properties of anti-β₂-glycoprotein I autoantibodies. Thromb Haemost 1998; 80: 393-8.
22 Reddel SW, Wang YX, Sheng YH, Krilis SA. Epitope studies with anti-β₂glycoprotein I antibodies from autoantibody and immunized sources. J Autoimmunity 2000; 15: 91-6.
23 Ambrozic A, Bozic B, Hojnik M, Kveder T. Improving an anti-β₂ glycoprotein I ELISA by reducing the influence of a blocking agent. Arthritis Res 2001; 03: A28 (abstract).
24 Brighton T, Dai Y-P, Hogg PJ, Chesterman CN. Microheterogeneity of β₂glycoprotein I: implication for binding to anionic phospholipids. Biochem J 1999; 340: 59-67.
25 Regnault V, Arvieux J, Vallar L, Lecompte T. Immunopurification of human β₂-glycoprotein I with a monoclonal antibody selected for its binding kinetics using a surface plasmon resonance biosensor. J Immunol Methods 1998; 211: 191-7.
26 Arvieux J, Regnault V, Hachulla E, Darnige L, Berthou F, Youinou P. Oxidation of β₂-glycoprotein I (β₂GPI) by the hydroxyl radical alters phospholipid binding and modulates recognition by anti-β₂GPI autoantibodies. Thromb Haemost 2001; 86: 1070-6.