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

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

Methods: 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).

Results: 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).

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