1023 IgA RHEUMATOID FACTOR (RF) IN HENOCH-SCHONLEIN PURPURA (HSP)

Abstract

Recent evidence indicates that circulating immune complexes play a role in the pathogenesis of HSP. The elaboration of RF appears to be an important host response to circulating immune complexes. Accordingly, sera from 23 children with acute HSP were tested for RF of various isotypes using a diffusion-in-gel enzyme-linked immunosorbant assay. Controls consisted of 15 normal children and 10 normal adults. Heat aggregated human or rabbit IgG was used for the test substrate and peroxidase-conjugated F(ab')2 fragment of goat anti-human IgG, IgA, or IgM served to determine the RF isotype. None of the HSP patients had IgG or IgM RF. Of the controls, one child had IgM RF, and one adult had IgG RF. IgA RF was present in the sera of 12 of 23 HSP patients (52%), in contrast to 1 of 25 controls (p<0.0005). When present, IgA RF titers tended to be highest during the acute phase of the illness. Although 64% of HSP patients had increased serum concentrations of IgA, there was no correlation between IgA concentration and the titer of IgA RF (r=0.25, p>0.10). Moreover, there was no association between the presence of IgA RF and any of the clinical manifestations of HSP such as nephritis, arthritis, abdominal pain, or gastrointestinal bleeding. These results indicate that a substantial proportion of HSP patients have IgA RF. The role of IgA RF in the formation of circulating immune complexes in HSP remains to be elucidated.