Immunohistochemical and immunocytochemical localization of .ALPHA.2u-globulin in the kidneys of female rats.

Abstract

We investigated the presence of α2u-globulin, which has generally been thought to be a protein specific to male rats, in the kidneys of female rats. Immunohistochemical, immunoelectron microscopic and immunochemical studies were performed on the kidneys of male and female F344 rats using rabbit anti-serum prepared with α2u-globulin purified from male rat urine. In male rats, hyaline droplets containing granules positive for immunohistochemical staining of α2u-globulin were observed in the proximal convoluted tubular epithelium. In females, fine granules positive for staining of α2u-globulin were observed in the same region, although so-called hyaline droplets were not observed in HE-stained specimens. Upon immunoelectron microscopic examination, gold particles indicating the presence of α2u-globulin were found localized in the lysosomes of proximal convoluted tubular epithelial cells in both sexes. Furthermore, immunohistochemistry revealed that α2u-globulin was localized in the submaxillary glands in both sexes and in the liver in males. In the immunochemical study, a double immunodiffusion test, precipitin lines were formed between the anti-serum and the kidney preparation and between the anti-serum and the submaxillary gland preparation from female rats. Spur formation was observed between the precipitin lines for the anti-serum and the submaxillary gland preparation and the precipitin lines for the anti-serum and urine in female rats; therefore, a partial difference in the antigenicity of α2u-globulin between males and females was suggested. From these results, we concluded that α2u-globulin exists in the kidneys in the female rats, and it is considered to originate mainly from the submaxillary glands, not the liver.