ELISA results
| Seropositive APS (n=40) | SN-APS (n=40) | |
|---|---|---|
| Standard ELISAs | ||
| No. (%) testing positive for IgG anti-CL | 18 (45%) | 0 |
| No. (%) testing positive for IgG anti-β2GPI | 6 (15%) | 0 |
| No. (%) testing positive for IgM anti-CL | 4 (10%) | 0 |
| No. (%) testing positive for IgM anti-β2GPI | 9 (22.5%) | 0 |
| Anti-DI ELISAs | ||
| No. (%) testing positive for IgG anti-DI | 11 (27.5%) | 3 (7.5%)* |
| No. (%) testing positive for IgM anti-DI | 9 (22.5%) | 0 |
| No. (%) testing positive for IgA anti-DI | 7 (17.5%) | 0 |
| Other IgA ELISAs | ||
| No. (%) testing positive for IgA anti-CL | 12 (30%) | 0 |
| No. (%) testing positive for IgA anti-β2GPI | 8 (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.