Increased OX40 and soluble OX40 ligands in children with Henoch-Schonlein purpura: association with renal involvement.

Henoch-Schonlein purpura (HSP) is one of the most common types of vasculitis disorders in childhood and is characterized by a rash, arthritis, abdominal pain, and renal involvement. T-lymphocyte activation is considered to play a critical role in vasculitis. However, the regulation of the T cells in HSP remains poorly understood. In this study, OX40/OX40L (CD134/CD252) costimulatory pathway, which could promote T-cell activation and long survival, was investigated. Results from 32 HSP patients and 25 healthy donors revealed that the freshly isolated CD4(+) T cells from patients with HSP expressed higher OX40 than that of the cells from healthy individuals. The levels of soluble OX40L (sOX40L) in the sera of patients with HSP were also much higher than the controls. Importantly, significantly elevated levels of OX40 on CD4(+) T cells and sOX40L in sera were detected in patients with HSP with nephritis compared to patients without nephritis, indicating both OX40 upregulation and sOX40L increase were closely associated with disease activity of the patients. Thus, circulating sOX40L could provide excessive costimulatory signal for CD4(+) OX40(+) T-cell activation, and OX40/OX40L signal might contribute to the development of HSP disease.