Exploring the plasmatic platelet-activating factor acetylhydrolase activity in patients with anti-phospholipid antibodies

PURPOSE: To explore the role of plasmatic platelet-activating factor acetylhydrolase (PAF-AH), a marker of cardiovascular risk, in patients with anti-phospholipid antibodies (aPL). METHODS: PAF-AH activity was assessed in a series of 167 unselected patients screened for aPL in a context of thrombotic events, risk of thrombosis or obstetric complications and in 77 blood donors. RESULTS: 116/167 patients showed positive results for at least one aPL among IgG/IgM anti-prothrombin/phosphatidylserine (aPS/PT), anti-cardiolipin (aCL), anti-beta2-glycoprotein I (aβ2GPI) or lupus anticoagulant (LAC), while 51/167 patients resulted aPL-negative. LAC+ patients disclosed higher PAF-AH than LAC-negative (22.1 ± 6.4 nmol/min/ml vs. 19.5 ± 4.1 nmol/min/ml; p = 0.0032), and aPL-negative patients (p = 0.03). Patients presenting positive IgG aβ2GPI disclosed higher PAF-AH than patients with only IgM aβ2GPI-positive antibodies (23.1 ± 7.2 nmol/min/ml vs. 20.1 ± 5.3 nmol/min/ml; p = 0.035), as well as than patients showing only isolated LAC, aCL or aPS/PT (16.9 ± 3.8 nmol/min/ml; p = 0.003). CONCLUSIONS: PAF-AH plasmatic activity is particularly up-regulated in LAC+ and in aβ2GPI IgG+ patients, possibly representing an alternative prognostic biomarker for the therapeutic management of APS patients.