Cpa3-Cre; Mcl-1fl/fl mice have markedly reduced basophil-dependent tissue swelling and leukocyte recruitment in IgE-dependent CAI. (A) Cpa3-Cre; Mcl-1fl/fl mice (n = 10), and Cpa3-Cre; Mcl-1+/+ control mice (n = 14) were sensitized passively by IV injection of 300 μg of IgE anti-TNP. Mice were challenged the next day by intradermal injection of 10 μg of TNP-OVA into the left ear pinna and OVA (as a control) into the right ear pinna. Ear swelling was measured daily and the results are shown as means ± SEM. The data shown were pooled from the 3 independent experiments performed, each of which gave similar results. *P < .05; **P < .01; and ***P < .001 comparing swelling in ears of IgE-treated Cpa3-Cre; Mcl-1fl/fl mice versus corresponding values for Cpa3-Cre; Mcl-1+/+mice at the indicated time points. P < .0001 by 2-way ANOVA comparing the ear swelling responses in IgE-injected Cpa3-Cre; Mcl-1fl/fl versus Cpa3-Cre; Mcl-1+/+ mice. (B) Immunohistochemical visualization of basophils by staining with an anti-mMCP8 Ab (DAB substrate) and Giemsa counterstaining (top panel, in 4-μm-thick, paraffin-embedded sections) and H&E staining to demonstrate leukocytes (bottom panel, in 4-μm-thick, paraffin-embedded sections) in ear pinnae 3 days after induction of CAI reactions. There are markedly decreased numbers of basophils (brown) and leukocytes in sections from Cpa3-Cre; Mcl-1fl/fl mice (right) versus Cpa3-Cre; Mcl-1+/+ control mice (left) subjected to CAI. Scale bars indicate 100 μm (for insets, scale bars indicate 25 μm); *, ear cartilage; e, epidermis. Images were captured with an Olympus BX60 microscope with a 20× objective using a Retiga-2000R QImaging camera run by Image-Pro Plus Version 6.3 software (Media Cybernetics) and exported into Adobe Photoshop (CS3), in which images were white balanced and resized.
