Background Henoch–Schönlein purpura (HSP) is a small-vessel vasculitis characterized by palpable purpura on the lower extremities and IgA-dominant immune complex deposition within the wall and lumen of dermal vessels in the lesions. This disorder is associated, to varying degrees, with joint, gastrointestinal and renal involvement. Antiphospholipid antibodies, including anticardiolipin antibodies (aCL Abs), are a heterogeneous group of circulating autoantibodies found in patients with autoimmune and infectious diseases.
Objectives To investigate the possible role of aCL Abs in adult HSP, we measured levels of serum IgA, C-reactive protein (CRP), aCL Abs of the IgG, IgM and IgA isotypes and anti-β2-glycoprotein I (β2GPI)-dependent aCL Abs in adult patients with HSP. We evaluated the correlation between these biological parameters and the clinical manifestations.
Methods Adult patients with HSP with an initial cutaneous manifestation of palpable purpura on their lower extremities seen between 2001 and 2005 in our department were retrospectively reviewed. Patients with known connective tissue diseases were not included in the study. Histological examination of all patient skin biopsy specimens revealed leucocytoclastic vasculitis in the upper and mid-dermis. Direct immunofluorescence analysis showed prominent deposits of IgA in the capillary walls of all patients. Blood samples were taken at the time that the patient presented. Serum levels of aCL Abs and anti-β2GPI-dependent aCL Abs were measured by enzyme-linked immunosorbent assay.
Results Twenty adult patients with HSP (12 men and eight women), mean age 62·2 years (range 23–81) were enrolled. IgA aCL Abs were found in 15 of the 20 patients (75%). All were negative for IgG aCL Abs, IgM aCL Abs and anti-β2GPI-dependent aCL Abs. The elevation of serum IgA aCL Abs in the 15 patients showed a significant correlation with serum IgA and CRP levels (rs = 0·91, P = 0·0007; rs = 0·80, P = 0·0026, respectively). Levels of serum IgA aCL Abs were also significantly associated with arthralgia (P = 0·022) and proteinuria according to urinalysis (P = 0·013).
Conclusions Serum levels of IgA aCL Abs are elevated in the initial active stage of adult HSP, suggesting that serum IgA aCL Abs may play some role in the onset of adult HSP. We believe that serum IgA aCL Abs might be an indicator of adult HSP activity.