FIGURE 1.
WeeB mast cells have intermediate growth properties. Bone marrow cells were harvested from wt, WeeB, and lyn−/− mice and grown in media containing IL-3 for 4–6 wk. A, Surface expression of FcεRI and c-Kit on 4-wk-old BMMCs derived from B6, WeeB, and lyn−/− mice was assayed by flow cytometry. B, Total cell number was determined during weekly media changes to track the growth of bone marrow cells cultured in IL-3-containing medium. Data represent means and SD. *p<0.05 versus lyn−/− cells. C, BMMCs >4-wk-old were grown in the indicated concentrations of IL-3 or SCF in the presence of [3H]thymidine for 5 h to measure cell proliferation. D, Apoptosis after IL-3 withdrawal was measured by Annexin V and 7-amino-actinomycin D staining using flow cytometry. The percentage of double-negative cells is plotted as a function of incubation time. *p <0.001 versus lyn−/− cells. Representative results from at least three independent experiments are presented.