Administration of rTFF2 to naive mice induces eosinophilia through an IL-33–dependent mechanism. (A) Naive IL-4 fluorescent reporter mice (4Get) were administered four daily i.p. injections of 1 µg rTFF2 or PBS and analyzed on day 5, and the percentage of inflammatory leukocytes from cytospin preparations of peritoneal lavage fluid were determined by Giemsa staining. Means ± SE of four mice per group are shown (**, P < 0.01). (B) Flow cytometry dot plots showing the gating strategy used to identify GFP⁺Siglec-F⁺ cells within the peritoneal cavity after the same treatments as described in A, but combined with the administration of anti-ST2 mAb or isotype-matched control Ig on days 0, 2, and 4. The percentage of total cells within the gated population is shown in the top right corner of each plot. The bottom plots are gated on cells shown within the corresponding top plot gates. Data represent mean ± SE of four mice/group. Data are representative of two to three independent experiments.