Immunohistochemical Study of Gamma-Glutamyl Transpeptidase with Monoclonal Antibodies. II. An Immunoelectron Microscopic Study in Rat Kidney

The localization of gamma-glutamyl transpeptidase (γ-GTP) in the rat kidney was examined by immunoelectron microscopy using monoclonal antibody to rat γ- GTP. The enzyme was distributed along the brush border and in the apical canaliculi and vacuoles of the proximal tubules. The immunoreaction of γ-GTP in the brush borders increased from the S₁ to S₃ segments in the proximal tubules. Conspicuousγ;-GTP immunostaining was observed along the basolateral membranes of the S₂ and S₃ segments of the proximal tubules. In addition, the apical cell membrane of the upper part of descending thin limbs of Henle's loops exhibited positive γ-GTP immunostaining. A faint reaction was occasionally recognized in the apical cell membranes of the distal convoluted cells, including the macula densa.