Interstitial lung disease (ILD) is a rare complication of antiphospholipid syndrome (APS), but circulating antiphospholipid antibodies have been detected in patients with ILD without APS. Whether antiphospholipid antibodies are associated with subclinical ILD phenotypes is unknown. We aim to examine the associations between anticardiolipin (aCL) and B-2 glycoprotein-1 (B2GP1) isotypes and high attenuation areas (HAA) and interstitial lung abnormalities (ILA) on CT scans in the Multi-Ethnic Study of Atherosclerosis (MESA).

We measured serum aCL and B2GP1 isotypes and calculated proportion of HAA on cardiac CT scan in 6623 MESA participants at baseline. The presence of ILAs were assessed on full lung CT scans at Exam 5. We used linear and logistic regression to examine these associations. We examined interactions by age, race, and smoking status.

In adjusted models, every doubling of aCL IgA, IgG, and IgM was associated with 0.36% (95% CI 0.03 to 0.70), 0.31% (95% CI 0.08 to 0.54), and 0.30% (95% CI 0.10 to 0.50) higher HAA in White participants, respectively. No association was found in participants of other races/ethnicities. Smoking modified the association between B2GP1 isotypes and HAA: in individuals with moderate smoking history, every doubling of B2GP1 IgA, IgG and IgM was associated with 0.84% (95% CI 0.30 to 1.38), 0.97% (95% CI 0.43 to 1.52) and 0.65% (95% CI 0.11 to 1.20) higher HAA, respectively. There was no association between antiphospholipid antibodies and ILA.

Antiphospholipid antibodies are associated with HAA, a quantitative measure of lung injury, inflammation and fibrosis.