August 08/13: anti-Phospholipid antibodies – time to take another look at IgA?
- IgA anti-Phospholipid antibodies may be present in isolation and often have clinical significance.
- New findings suggest that further specific investigations into these antibodies may assist with risk stratification in APS and SLE patients.
Andreoli A, Fredi M, Nalli C, Piantoni S, Reggia R, Dall’Ara F, Franceschini F, Tincani A Clinical Significance of IgA Anti-Cardiolipin and IgA Anti-β2Glycoprotein I Antibodies
Curr Rheumatol Rep (2013) 15:343 DOI 10.1007/s11926-013-0343-1
Background: Experimental data has shown the pathogenic role of IgA anti-cardiolipin antibodies, however, they are not currently recognized as formal laboratory criteria for the Antiphospholipd Syndrome (APS), possibly because of the non-standardization of IgA assays and the differences in study designs. Nevertheless, IgA antibodies are occasionally the only antibodies present in APS patients and IgA anti-β2Glycoprotein are significantly associated with thrombotic events in SLE patients.
Summary: This review article brings together new studies on the clinical significance of IgA antibodies in APS, pregnancy loss and thrombotic events in SLE. It also looks at antibodies to a specific domain area of β2Glycoprotein as a new and clinically relevant subgroup of antiphospholipid antibodies (aPL).
Conclusions: The heterogeneity of published data around the clinical significance of IgA aCL has meant that this association is still controversial. However, testing for IgA aCL can be recommended in cases for which there is a strong suspicion of APS but other aPL tests are negative. IgA anti-β2GPI, on the other hand, seem to be the most prevalent isotype in patients with SLE, with a significant association with thrombotic events. Systemic Lupus International Collaborating Clinics (SLICC) have recognised the IgA antibodies’ importance by allowing both IgA aCL and IgA anti- β2Glycoprotein as valid tests for the definition of SLE. The novel suggestions that IgA anti- β2Glycoprotein D4/5 may be relevant autoantibodies in APS and SLE gives a good direction for future research with particular focus on the fine specificity of aPL.
Comment: This review updates the current available information on the relevance of IgA autoantibodies in autoimmune thrombotic disorders. The authors urge awareness of the possibility that these antibodies may be the sole markers present and that their presence may well correlate with clinically significant thrombotic events, particularly true for IgA anti-β2Glycoprotein, and so their detection is well warranted. On the basis of available studies cited here, they encourage specialists to carefully consider treatment options in patients presenting with isolated IgA APL. They also suggest that these antibodies should be further researched.