Some properties of cells cultured from early-lactation human milk

Cells that can be cultured from pools of early-lactation milk were studied. Under the culture conditions used, the majority of cells attached to collagen-coated dishes; most of these remained single, did not divide, and in their adhesiveness, phagocytic ability, and ultrastructure resembled macrophages or histiocytes. On a plate seeded with approximately 3 X 10(5) cells, however, 10-100 colonies of dividing cells developed. These cells had the junctional complexes typical of epithelial cells and grew well in a medium supplemented with human serum and hydrocortisone for 16-20 days after seeding. After removal of serum from the medium, some cells continued to traverse the cell cycle, and the colonies containing these cells were morphologically distinct from those which became quiescent. The nondividing cells in milk could be separated from the milk epithelial cells and were able to stimulate the growth of epithelial cultures from benign mammary dysplasias.