The aim of the present study was to develop long-term culture conditions for foreskin-derived mast cells (HSMC) as we have previously done for rodent peritoneal mast cells (MC) and human lung-derived MC. HSMC were obtained by proteolytic treatment of foreskins from 8-day-old babies (4.8 +/- 2.0% purity) and seeded onto a confluent monolayer of human foreskin-derived fibroblasts (HF) in enriched culture medium. HSMC biochemical and functional properties were studied up to 8 days in these cocultures. Twenty-four hours after seeding the cell suspensions from the proteolytic-digested foreskins, all the cells which did not adhere to the HF were washed out. At this time point approximately 30% of the seeded HSMC were found to adhere to the HF monolayer. The only contaminating cells were endothelial cells (< 8%). Cocultured HSMC maintained their normal resting morphology and histamine content (3.1 +/- 0.7 pg/cell) up to 8 days in these cocultures. When challenged with compound 48/80 on Days 1, 2, 4, and 8 of coculture, HSMC released similar percentages of histamine which were comparable to the one released by freshly isolated HSMC in suspension (approximately 30%). Similarly, HSMC, sensitized with IgE antibodies and challenged at various time of coculture with anti-IgE antibodies, released throughout the experiment comparable percentages of this mediator (approximately 50%). Thus, coculture of HSMC with HF fibroblasts provides a suitable in vitro system for long-term studies on HSMC functional and biochemical properties in a microenvironment which mimics the physiologic one.