Detection of P-glycoprotein with four monoclonal antibodies in normal and tumor tissues
Z. P. Pavelic, J. Reising, L. Pavelic, D. J. Kelley, P. J. Stambrook and J. L. Gluckman
Department of Otolaryngology-Head and Neck Surgery, College of Medicine, University of Cincinnati, Ohio 45267-0528.
P-glycoprotein (Pgp), encoded by the multidrug-resistance gene (MDR1), is
an active efflux pump for many structurally diverse lipophilic compounds.
Using peroxidase-antiperoxidase immunohistochemistry technique and four
anti-Pgp monoclonal antibodies directed against different epitopes of the
molecule, we examined the distribution of Pgp in normal human tissues and
squamous cell carcinomas of the head and neck. All four antibodies detected
Pgp in bronchial cells, mammary ductal epithelium, gallbladder epithelium,
epithelia of small and large intestine, bile canaliculi, dermal sweat
glands, proximal tubules of kidney, endometrium, trophoblasts, adrenal
gland, and capillaries of central nervous system, testis, and papillary
dermis. Of the 23 head and neck squamous cell carcinomas, about 60% had
detectable Pgp. It is possible that differences noticed between antibodies
are due to cross-reactivity to proteins unrelated to MDR1. Care must be
taken in interpreting staining results when only one or two monoclonal
antibodies are used.
