Figure 6.

Flow cytometry reveals that changes in basophil numbers do not account for increases in histamine in mycoplasma-infected mice. (A) These representative plots compare surface expression of CD131 (β chain common to receptors for IL-3, IL-5, and GM-CSF), IgE, and c-kit in lung cells from +/+ and W-sh mice. These data are from mice studied 14 d after sham or mycoplasma infection. The percentage of cells in specific gates (boxed) is indicated. Basophils are CD131 and IgE positive but express little or no c-kit, distinguishing them from mast cells. In lungs from all types of mice, the CD131⁺/IgE⁺ subset (gated as noted) was a small but distinct population of extractable cells, consisting almost entirely of c-kit⁻ and c-kit^lo cells. As shown in the lower right panel inset, these cells feature basophilic granules with segmented nuclei. (B) The number of basophils per lung 7 and 14 d after infection was calculated by multiplying total cells by the fraction of CD131⁺/IgE⁺ cells. Data are mean ± SE; n = 3 animals per group; *, P < 0.05 in comparison with uninfected W-sh.