Table 2

ELISA results

Seropositive APS (n=40)SN-APS (n=40)
Standard ELISAs
 No. (%) testing positive for IgG anti-CL18 (45%)0
 No. (%) testing positive for IgG anti-β2GPI6 (15%)0
 No. (%) testing positive for IgM anti-CL4 (10%)0
 No. (%) testing positive for IgM anti-β2GPI9 (22.5%)0
Anti-DI ELISAs
 No. (%) testing positive for IgG anti-DI11 (27.5%)3 (7.5%)*
 No. (%) testing positive for IgM anti-DI9 (22.5%)0
 No. (%) testing positive for IgA anti-DI7 (17.5%)0
Other IgA ELISAs
 No. (%) testing positive for IgA anti-CL12 (30%)0
 No. (%) testing positive for IgA anti-β2GPI8 (20%)1 (2.5%)*
  • The cut-off for positive in each assay was defined as 99th centile of the healthy control population.

  • *The titres of IgG anti-DI in the three positive patients were 16 absorbance units (AU), 15.3 AU and 22.2 AU respectively compared with the positive cut-off of 10 AU. The titre of IgA anti-β2GPI in the one positive patient was 16 AU compared with a positive cut-off of 9 AU.

  • anti-β2GPI, anti-β-2-glycoprotein; CL, cardiolipin; DI, domain I; Ig, immunoglobulin; SN-APS, seronegative antiphospholipid syndrome.