CHARACTERIZATION OF CORD-BLOOD-DERIVED HUMAN MAST-CELLS CULTURED IN THE PRESENCE OF STEEL FACTOR AND INTERLEUKIN-6

We generated >10(7) mast cells by culturing 10(7) cord blood mononucle ar cells for >10 weeks in the presence of Steel factor, interleukin-6 and prostaglandin E(2). 99% of the cultured cells had tryptase-positiv e granules, while 18% had chymase-positive granules. Cultured mast cel ls contained 3.6 mu g histamine and 3.5 mu g tryptase per 10(6) cells. Cells sensitized with 1 mu g/m1 human IgE released 58.5% histamine an d 1.55 ng tumor necrosis factor (TNF)-alpha per 10(6) cells when chall enged with 1 mu g/ml antihuman IgE, whereas the control cells spontane ously released 3.7% histamine and 0.18 ng TNF-alpha. Analysis for surf ace antigens revealed that cultured mast cells expressed the following CD molecules: 9, 13, 14, 29, 33, 38, 43, 44, 45RA, 45RB, 46, 47, 48, 49d, 50, 51, 53, 54, 55, 58, 59, 60, 61 and 117 (c-kit). Taken togethe r, these cultured cells seem to be functionally mature mast cells.