In vivo binding of immunoglobulin and complement to elastic structures in urinary bladder vascular walls in interstitial cystitis: demonstration by immunoelectron microscopy.

An ultrastructural immunoperoxidase staining technique was used to identify and localize immune deposits in the urinary bladder vessel walls of patients with interstitial cystitis. Deposition of immunoglobulin together with the C3 component of complement was found in the subendothelial space and in endothelial basement membranes. More peripherally, deposits were often found associated with elastic fibers between smooth muscle cells. In these fibers the staining was confined to the microfibrillar coat. The findings suggest that elastic microfibrils act as target sites for the immunologic reaction occurring in vivo. Following binding of autoantibodies to antigens in bladder mucosa, activation of complement could be involved in the production of tissue injury and in the chronic self-perpetuating inflammation typical of this disease.