Human mast cells but not human basophils coculture with mouse 3T3 fibroblasts

Abstract

Human mast cells and basophils have been shown to arise from CD34+ pluripotent progenitor cells in the presence of rhIL-3 (1). Two different culture systems using CD34+ cells, the agarose interphase culture and 3T3 fibroblast/CD34 + coculture, give rise to mast cells and basophils but with markedly different results. (1,2). By 3 weeks in interphase agarose cultures, CD34+ cells give rise to approximately 25-45% basophils and 1-5% tryptase positive mast cells. These mast cells have homogeneous granule patterns that resemble immature mast cells. With the addition of stem cell factor (rhSCF) (3) to rhIL-3, total cell number increases and mast cell maturation is promoted without altering the percentages of mast cells and basophils (4). These mast cells have tryptase-positive granules, with characteristic patterns seen in mature mast cells. In contrast, CD34+ cells cocultured with mouse 3T3 fibroblasts give rise by 6 weeks to approximately 50% tryptase positive mast cells which adher to the monolayer and possess granule scroll patterns. No basophils are ever identified by six weeks in cocultures.