Identification of mouse mammary epithelial cells by immunofluorescence with rabbit and guinea pig antikeratin antisera.

Abstract

Few markers are available to identify the 3 types of mammary epithelial cells.sbd.ductal, alveolar and myoepithelial.sbd.especially in pathological conditions and in cell cultures. Antisera to human keratins were used in immunofluorescence to facilitate the identification of the 3 mouse mammary epithelial cell types. In frozen tissue sections and primary cell cultures, a rabbit antikeratin antiserum specifically stained cytoplasmic filaments in all 3 types of epithelial cells. A guinea pig antiserum against the same keratin preparation reacted preferentially with filaments in myoepithelial cells and readily detected this cell type in normal, dysplastic and malignant mammary tissues and cell cultures. Neither antisera reacted with fibroblasts or any other mesenchymal cells. The combined use of the 2 antikeratin antisera thereby permits rapid surveys of tissue sections and cultures for the localization of not only all epithelial cells but also the subpopulation of myoepithelial cells. When mammary cultures established from late-pregnant or lactating mice were stained simultaneously with guinea pig antikeratin and rabbit anticasein antisera, 3 populations of epithelial cells were mutually exclusive: those stained by anticasein antiserum, those stained by guinea pig antikeratin antiserum and those stained by neither, consistent with properties of alveolar, myoepithelial and ductal cells, respectively. These antisera thus offer a tool for studying different epithelial cell types during mammary development, tumorigenesis and malignant progression.