Can Immunoglobulin IgA levels predict the Anticardiolipin isotypeM antibody positivity?
Mohamad A. Ayass, MD, Gul Nowshad, MD, MPH, Ph.D. Ayass Lung Clinic & Sleep Center, TX, USA.
According to Sydney criteria for a diagnosis of Antiphospholipid syndrome (APS) any one of the laboratory assays: LA, aCL IgG and IgM, and anti-β2GPI IgG and IgM needs to be abnormal. Recent research has emphasized the importance of IgA a B2GPI antibodies in APS as well but none of the studies have explored the association of immunoglobulin A levels and APL syndrome/ aCL positivity.
Methods: Four hundred patients examined at Ayass Lung Clinic & Sleep Center in 2013 were included in the study to analyzed immunoglobulin levels and their association with other biomarkers and diseases. Demographic, clinical, and laboratory information were obtained from medical records. Logistic regression models were employed to determine association between risk factors and the Anticardiolipin antibody positivity for both aCL IgM and aCL IgG. aCL titers were categorized into negative (0-10 U/L) and positive ( > 10 U/L).
Results: There were 158 patients (40%) aCL IgM positive and 87 (22%) aCL IgG positive titers. Ninety percent aCL IgM positive patients were (>50 years) with a mean age of 64 years, 57% females and 76% were White. Eighty seven percent of aCL IgM positive were IgA deficient and mean IgA levels were 218 in aCL IgM positive patients compared to 247 in aCL IgM negative patients.
Analysis for aCL IgG showed that only being female was associated with the positive aCL IgG antibodies. Regarding analysis for aCL IgM, patients who are deficient in IgG (<750) were 1.7 times (CI, 1.02-2.80) more likely to become aCL IgM positive in unadjusted analysis but after controlling for age, gender and ethnicity the association was not significant. While patients with immunoglobulin IgA level< 453 were 1.8 times more likely to be positive for aCL IgM after adjusting for age, gender and ethnicity.
Research has established the fact that IgA deficiency will predispose individuals to recurrent infection but its association with aCL may make IgA deficient patient to be vigilant about thrombotic risks beside malabsorption and infection. aCL Abs may be elevated in response to infection due to decreased immunity so further studies are indicated to delineate the mechanism and the association between immunoglobulin and aCL antibodies.