Characterization of cord-blood-derived human mast cells cultured in the presence of Steel factor and interleukin-6.

We generated > 107 mast cells by culturing 107 cord blood mononuclear cells for > 10 weeks in the presence of Steel factor, interleukin-6 and prostaglandin E2. 99% of the cultured cells had tryptase-positive granules, while 18% had chymase-positive granules. Cultured mast cells contained 3.6 μg histamine and 3.5 μg tryptase per 106 cells. Cells sensitized with 1 μg/ml human IgE released 58.5% histamine and 1.55 ng tumor necrosis factor (TNF)-α per 106 cells when challenged with 1 μg/ml antihuman IgE, whereas the control cells spontaneously released 3.7% histamine and 0.18ng TNF-α. Analysis for surface 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 together, these cultured cells seem to be functionally mature mast cells.