Identification of myoepithelial cells in human and rat breast by anticommon acute lymphoblastic leukemia antigen antibody A12

ABSTRACT-An immunohistological study in the human breast and the rodent breast (from inbred LudwiglWistar/Olac rats) was conducted with the use of a murine monoclonal antibody, which reacts with the common acute lymphoblastic antigen, a glyco-sylated polypeptide of a molecular weight of 100,000. The epitope, as recognized by this antibody, is expressed on myoepithelial cells of the normal human and rat breasts and was studied in the devel-oping rodent mammary gland. Ultrastructural studies in the normal human breast clearly demonstrated the presence of the antigen on the lateral membrane of the myoepithelial cells with no staining of luminal cells, blood vessels, or stromal elements. The antigen sur-vived prolonged enzymatic digestion of human breast tissue and could be demonstrated on myoepithelial cells in single-cell sus-pensions of human breast where it stained approximately 3-14 % of the total cell population. The presence of this antigen on myo