Funding sources This work was supported by National Taiwan University Hospital (grant number: 98HM00021) and National Science Council of Taiwan (grant number: NSC 100-2314-B-002-095-MY3).
Identification and characterization of IgA antibodies against β2-glycoprotein I in childhood Henoch–Schönlein purpura
Article first published online: 5 SEP 2012
© 2012 The Authors. BJD © 2012 British Association of Dermatologists
British Journal of Dermatology
Volume 167, Issue 4, pages 874–881, October 2012
How to Cite
Yang, Y.H., Chang, C.J., Chuang, Y.H., Hsu, H.Y., Yu, H.H., Lee, J.H., Wang, L.C., Lin, Y.T. and Chiang, B.L. (2012), Identification and characterization of IgA antibodies against β2-glycoprotein I in childhood Henoch–Schönlein purpura. British Journal of Dermatology, 167: 874–881. doi: 10.1111/j.1365-2133.2012.11068.x
Conflicts of interest None declared.
- Issue published online: 26 SEP 2012
- Article first published online: 5 SEP 2012
- Accepted manuscript online: 25 MAY 2012 10:30AM EST
- Accepted for publication 16 May 2012
Background Henoch–Schönlein purpura (HSP) is a common IgA-mediated vasculitis in children. The antigenic target for IgA is to be determined.
Objective To test whether β2-glycoprotein I (β2GPI) is an antigenic target for IgA in childhood HSP, and to evaluate the clinical implications and pathogenic role of such IgA autoantibodies.
Methods The reactivity of patients’ plasma samples and purified polyclonal IgA with β2GPI, β2GPI-derived peptides and endothelial cells was tested by enzyme-linked immunosorbent assay. The association between clinical manifestations and IgA anti-β2GPI antibodies was also analysed. Finally, IgA-mediated cytotoxicity on endothelial cells was further evaluated.
Results At the acute stage, patients with HSP had significantly higher plasma levels of IgA antibodies against β2GPI than healthy controls [reference units (RU) 1·14 ± 0·8 vs. 0·42 ± 0·24, P < 0·001]. IgA anti-β2GPI antibodies were associated with the presence of joint manifestations (with vs. without joint involvement, 1·15 ± 0·64 vs. 0·85 ± 0·47, P = 0·0341) and heavy proteinuria (with vs. without heavy proteinuria, 2·09 ± 2·02 vs. 1·04 ± 0·62, P = 0·0028). Polyclonal IgA from plasma samples positive for IgA anti-β2GPI antibodies bound well not only to β2GPI with Kd values < 10−5 mol L−1, but also to some β2GPI-dereived linear peptides (P3, P5, P7, P11 and P12). Moreover, β2GPI-reactive polyclonal IgA also bound well to endothelial cells and induced complement-dependent cell lysis.
Conclusion These findings reveal the clinical and pathogenic relevance of IgA anti-β2GPI antibodies in childhood HSP and suggest that β2GPI may be an important autoantigen for HSP.