Pulmonary events in antiphospholipid syndrome: influence of antiphospholipid antibody type and levels

This prospective clinical study examined the association between subclasses of antiphospholipid antibodies (aPL) and pulmonary manifestations in antiphospholipid syndrome (APS).

The cohort involved 329 patients: 214 patients with primary APS (PAPS) and 115 patients with secondary APS (SAPS). aPL analysis included detection of serum anticardiolipin antibodies [aCL (IgG/IgM)], β₂ glycoprotein I [β₂GPI (IgG/IgM)], and lupus anticoagulant (LA).

In SAPS, high aCL IgG levels (> 100 PLU/mL) were more common in major pulmonary arterial thrombosis (p = 0.006) and medium aCL IgG levels (41-99 PLU/mL) in adult respiratory distress syndrome (ARDS; p = 0.047) and fibrosing alveolitis (p = 0.002). aCL IgG antibodies were more common in SAPS (p = 0.037). In PAPS, fibrosing alveolitis was more common in patients with medium β₂GPI IgM levels (p = 0.0001). LA correlated with pulmonary embolism (p = 0.03) and microthrombosis (p = 0.03) in SAPS, and with pulmonary microthrombosis (p = 0.03) in PAPS. Males were more likely to develop secondary pulmonary hypertension when diagnosed with PAPS (p = 0.019).

Certain classes of aPL are associated with distinct pulmonary manifestation, indicating their predictive role and importance in diagnosis and treatment of APS.