To clarify the role of apolipoprotein E (apo E) in the formation of amyloid deposits, we examined specimens from 11 patients with renal amyloidosis who underwent renal biopsy by an immunohistochemical method using a monoclonal antibody (murine IgG1). Apo E was distributed in the amyloid deposits of all patients in a pattern similar to that obtained with Congo red staining. Strong positive staining for apo E was found on the amyloid deposits in the glomeruli. These results suggest that apo E is a common constituent of amyloid fibrils and that it may be a useful marker for immunohistochemical studies of systemic amyloidosis including renal amyloidosis
