High titer of anti-phosphatidylserine-prothrombin complex antibodies in patients with cutaneous polyarteritis nodosa.

OBJECTIVE: To investigate possible correlations between cutaneous polyarteritis nodosa (CPN) and antiphospholipid syndrome-associated antibodies.

METHODS: Sixteen patients were referred with CPN features. To investigate the possible role of antiphospholipid antibodies (aPL) in CPN, we measured serum lupus anticoagulant (LAC), IgG and IgM anticardiolipin (aCL) and anti-phosphatidylserine-prothrombin complex (anti-PS/PT) antibodies, and anti-beta(2)-glycoprotein I-dependent cardiolipin (anti-beta(2)GPI/CL) antibodies in the 16 CPN patients, 8 microscopic polyangiitis (MPA) patients, 33 systemic lupus erythematosus (SLE) patients, and 23 healthy controls. LAC was determined according to the Subcommittee on Lupus Anticoagulant/Phospholipid Dependent Antibody guidelines. Anti-PS/PT, aCL, and anti-beta(2)GPI/CL antibodies were measured by enzyme-linked immunosorbent assay.

RESULTS: Anti-PS/PT antibodies and/or LAC were detected in all CPN patients, but not in any controls. Serum IgM anti-PS/PT antibody was found in 13 (81.3%) CPN patients. The mean +/- SD serum anti-PS/PT IgM level (19.9 +/- 12.4 units/ml) in CPN patients was significantly elevated compared with SLE patients (5.7 +/- 5.9 units/ml). IgG anti-PS/PT antibody was detected in 5 (31.3%) CPN patients, but not in any controls. The IgG PS/PT antibody titers were similar in CPN patients (12.3 +/- 12.0 units/ml) and SLE patients (13.8 +/- 14.3 units/ml). Three (18.8%) CPN patients were positive for IgG aCL antibody and 2 (12.5%) for IgM aCL antibody. No MPA patients had aPL. CPN skin manifestations included livedo reticularis (14 [87.5%]). Direct immunofluorescence (DIF) revealed C3 within the affected vessels in 7 (77.8%) of 9 CPN patients.

CONCLUSION: Our study demonstrated that presence of anti-PS/PT antibodies and/or LAC could serve as markers in CPN patients. CPN could be dependently associated with the presence of anti-PS/PT antibody. Clinicians need to recognize these titers to permit early accurate diagnosis and treatment. We believe that anti-PS/PT antibodies will become widely recognized as a new factor when diagnosing CPN.