Enzymatically dispersed skin cells were immunoaffinity purified with the R24 mAb against GD3, and then sorted with the anti-Kit YB5.B8 mAb using a Coulter Epics Cell Sorting System. Individual mast cells were sorted into each well of 96-well plates containing human fibroblast monolayers, and were then cultured in AIM-V medium containing 100 ng/mL rhuSCF. After 3 weeks of culture, mast cell numbers were determined by immunochemistry for tryptase with the G3 mAb. Results from 4 separate sorts, one plate per sort, are shown.