EFFECTS OF STAPHYLOCOCCUS-AUREUS TOXINS ON THE GROWTH OF BOVINE MAMMARY EPITHELIAL-CELLS (MAC-T) IN CULTURE

The effects of Staphylococcus aureus M60 culture supernatant on growth of mammary epithelial cells were tested in vitro. Exposure of MAC-T c ells to S. aureus culture supernatant reduced cell proliferation and c olony-forming ability because of reduced ability to adhere to plastic. Growth-inhibiting effects of S. aureus culture supernatant were aboli shed by pretreatment with trypsin. Lysis of S. aureus cells with lysos taphin demonstrated that the inhibition was also present in cell lysat es. Treatment of MAC-T cells with culture supernatant from isogeneic m utants of S. aureus M60 that produced either alpha or beta toxins impl icated alpha toxin as the main factor inhibiting cell proliferation.