Secretory IgA in Schönlein-Henoch purpura

2 young patients with Schönlein-Henoch purpura were investigated to detect secretory IgA and secretory component (SC) in skin lesions and urine in connection with the upper respiratory and intestinal symptoms at onset. In these cases, laboratory findings revealed relative leukocytosis, hematuria, and proteinuria in urinalysis, but no elevation of serum immunoglobulin levels and ASO titer. In biopsy specimens from purpuric lesions on lower extremities, leukocytoclastic vasculitis was found in the upper dermis histologically. Immunofluorescence showed deposits of IgG and IgA with SC and joining chain and complement at vessel walls in the upper dermis, and SC was deposited at the dermoepidermal junction. An attempt to concentrate urine from the patients revealed precipitin lines of IgG, IgA, and SC by using Ouchterlony's method. These observations suggest that in patients with Schönlein-Henoch purpura circulating immune complexes containing secretory IgA and SC deposits in skin lesions and kidney exist in connection with the initial involvements on the mucous membranes of the respiratory and/or intestinal tracts.