The Presence of IgM Antiphospholipid Antibodies in Patients With Henoch-Sch önlein Purpura and Recurrent Palpable Purpura FREE

Henoch-Sch önlein purpura (HSP) is a primary small-vessel vasculitis characterized by nonthrombocytopenic palpable purpura over the lower extremities. Our research group previously speculated that IgM antiphosphatidylserine-prothrombin complex (anti-PSPT) antibodies could be implicated in disease susceptibility for livedo racemosa.¹ Others have reported the presence of antiphospholipid antibodies in patients with cutaneous vasculitis, including HSP.^2- 3 Whether these antibodies represent an epiphenomenon or they are thrombogenic and/or vasculitic in origin in such patients is unknown.

We reviewed the records of Japanese patients with HSP who were seen at the Department of Dermatology, St Marianna University, Kawasaki, Japan, with the recurrent cutaneous manifestation of palpable purpura on their lower extremities between 2006 and 2010. The patients were diagnosed according to the criteria defined by the American College of Rheumatology⁴ and the KAWAKAMI algorithm.⁵ Recurrent palpable purpura was defined as the occurrence of slightly elevated purpura with palpable swelling numerous times during the 3-month follow-up. None of our patients demonstrated any evidence of a coexisting malignant neoplasm, other autoimmune disease, or viral hepatitis. Lupus anticoagulant (LAC) levels and/or the presence of anti-PSPT antibodies were measured according to previously described procedures.¹

We identified 12 consecutive patients with HSP and recurrent palpable purpura (4 men and 8 women), mean (SD) age, 32.7 (11.7) years) (Table). All patients demonstrated livedo racemosa over their lower extremities in association with the temporary disappearance of the palpable purpura (Figure). Seven of the 12 patients were shown to be LAC positive (58%). Eleven patients tested positive for IgM anti-PSPT antibodies (92%) but not IgG anti-PSPT antibodies. All the patients were LAC positive and/or demonstrated IgM anti-PSPT antibodies. Renal involvement was noted in 9 patients (75%), and gastrointestinal involvement was noted in 8 (67%). There were 7 patients with both renal and gastrointestinal involvement (58%) and also tested positive for IgM anti-PSPT antibodies.

We found that all patients with HSP except 1 woman with recurrent palpable purpura tested positive for IgM anti-PSPT antibodies. Livedo racemosa was found in all patients. We suggest that the link between recurrent palpable purpura and livedo racemosa in the present patients may be related to a common immunogenetic pathogenic pathway that includes IgM anti-PSPT antibodies.

Antiphospholipid antibodies likely cause vascular thrombosis by damaging the endothelium. However, there is a controversy whether these antiphospholipid antibodies per se cause a true necrotizing vasculitis. Patterson et al⁶ focus on the role of endothelial cell injury as a cofactor in the evolution of small-vessel vasculitis. Based on these findings, IgM anti-PSPT antibodies may be involved in damaging the endothelial cells, which could lead to the formation of recurrent palpable purpura as well as livedo racemosa.

More than half of patients with HSP who have recurrent palpable purpura also have both renal and gastrointestinal involvement. Serum IgM anti-PSPT antibody levels could be related to the common pathogenic factors that trigger the development of severe HSP, gastrointestinal symptoms, and HSP nephritis. As such, the IgM-antigen complex, as a heavy molecule, could be preferentially trapped in the capillaries of kidney and the digestive tract.