The immunobiology of Henoch-Schönlein purpura.

Henoch-Schönlein purpura (HSP) is a common but enigmatic systemic small vessel vasculitis that primarily affects children. Although the etiology of this disease is unknown, there are tantalizing clues on the natural history and immunopathogenesis. This article reviews these clues including aspects of disease-associated pathogens, immune regulation, with a focus on IgA, and finally the immunogenetic background of host. We also present a hypothetical model for the development of HSP and submit that this paradigm will be a generic one for similar vasculopathies.