Circulating IgA-immune complexes in XXXX . A longitudinal study of their relationship to disease activity and vascular deposition of IgA.

@entity1 @entity1333 @entity5417 @entity6300
In @entity5417 immune complexes in inflamed vessel walls characteristically contain immunoglobulin A(IgA). To determine whether IgA is also the predominant immunoglobulin in circulating immune complexes, we compared the results of three immune complex assays with specificities for different classes of immunoglobulins in a longitudinal study of 37 @entity1 (30 @entity1 and seven adults) with @entity5417 . Circulating IgA-containing immune complexes were detected by their reactivity with a low avidity anti-IgA antibody in 27 of the 37 @entity1 . IgA was simultaneously present in cutaneous vessel walls in 95 percent of the @entity1 with circulating IgA-containing immune complexes. High levels of IgA-containing immune complexes were found only during the initial phase of the disease. Immune complexes containing bound complement breakdown products were demonstrated by binding to conglutinin. IgA was found in these immune complexes in 17 patients, IgG in 17 and IgM in nine @entity1 . There was no apparent relation with the class of immunoglobulin in the deposits. Conglutinin-binding immune complexes were present later in the course of the disease and after remission. @entity6300 -binding immune complexes were only found in two @entity1 . These findings suggest that immune complexes-containing IgA may initiate the @entity1333 of @entity5417 , whereas complement-reacted immune complexes containing immunoglobulins of the other classes appear in the circulation in a later phase.
