IMMUNOHISTOCHEMICAL DETECTION OF P-GLYCOPROTEIN IN TELEOST TISSUES USING MAMMALIAN POLYCLONAL-ANTIBODIES AND MONOCLONAL-ANTIBODIES

Mammalian P-glycoprotein is a highly conserved 170-kD integral plasma membrane protein functioning as an energy-dependent efflux pump of exo genous and endogenous lipophilic aromatic compounds entering the cell by diffusion. In this study, the tissue specificities of one polyclona l (pAb) and three monoclonal (mAbs) antibodies to mammalian P-glycopro tein were identified in paraffin-embedded, parasagittal whole-body sec tions of the guppy Poecilia reticulata. Polyclonal antibody mdr(Ab-l) and mAbs C219, C494, and JSB-1 demonstrated differential staining patt erns in the following tissues: bile canaliculi in the liver, exocrine pancreas, lumenal surface of the intestinal epithelium, renal tubules, interrenal tissue, branchial blood vessels, gas gland, pseudobranch, and the gill transverse septa. Positive P-glycoprotein expression in P . reticulata correlates well with published results for homologous mam malian tissues of secretory and excretory function. These data indicat e that one or more highly conserved members of the P-glycoprotein tran sporter family exist in a teleost species and can be detected using co mmercially available mammalian antibodies. (C) 1995 Wiley-Liss, Inc.