SUBTYPES OF NONTRANSFORMED HUMAN MAMMARY EPITHELIAL-CELLS CULTURED IN-VITRO - HISTO-BLOOD GROUP ANTIGEN-H TYPE-2 DEFINES BASAL CELL-DERIVEDCELLS

Normal (non-transformed) human mammary epithelial cell lines derived f rom reduction mammoplasties were analyzed by immunocytochemistry with more than 80 monoclonal antibodies (mAbs) and other specific reagents to tissue-specific and developmentally regulated. antigens at differen t passage levels. A subpopulation of poorly differentiated, proliferat ing epithelial cells, corresponding to the 'selected' cell type of lat e passages, is shown to be characterized by a new marker, the histo-bl ood group antigen H type 2, probably carried on a membrane-bound glyco lipid. These cells also express a number of other onco-developmental c arbohydrate antigens [Le(y), Le(x), sialosyl-Le(a), precursor of Thoms en Friedenreich antigen (T(n)), but not Thomsen-Friedenreich antigen a nd sialosyl-T(n)]. Their cytokeratin (CK) phenotype, as assessed by re activity with monospecific mAbs and two-dimensional gel electrophoresi s, is CK 5, 6, 14 and 17, with CK 19 being consistently absent, and va rying minor amounts of CK 7, 8 and 18, as well as 15 and 16. The react ivity of these cells with a panel of 11 mAbs specific for CK 18 varies considerably even after cloning, indicating heterogeneity of epitope expression or accessibility. Our data strongly suggest that the H type 2+ cells develop from the basal cell layer of the mammary gland.