Localized amyloidosis of the seminal vesicle : Identification of lactoferrin immunoreactivity in the amyloid material

Three specimens of localized amyloidosis of the seminal vesicle surgically removed for prostatic cancer were immuno-histochemically analyzed to clarify the nature of the permanganate-sensitive congophilic subeplthelial deposition. A variety of known amyloidogenic substances and secretory products in the seminal fluid were screened using the indirect immunoperoxldase method. In addition to reactivities with antibodies to amyloid P component and human seminal plasma, the amyloid material was immunoreactive for lactoferrin using a rabbit antiserum and two of three mouse monoclonal antibodies. All the antibodies labeled some of the normal seminal vesicle epithelial cells for this iron-binding, bacteriostatJc glycoprotein. In the prostate without accompanying amyloid deposition, a considerable proportion of the glandular epithelium and secretory material were positive for lactoferrin. Pre-embedding immunoelectron microscopy showed lactoferrin immunoreactivity on the amyloid fibrils. Focal staining of the amyloid for gross cystic disease fluid protein-15 was also observed in two lesions. These findings strongly suggest that lactoferrin is the major constituent in localized senile amyloidosis of the seminal vesicle.