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. 2018 Jul 3;9:1540. doi: 10.3389/fimmu.2018.01540

Figure 3.

Figure 3

Histamine derived from basophils but not mast cells is crucial for the manifestation of acquired tick resistance. (A) Bone marrow-derived basophils and bone marrow-derived mast cell (BMMCs) generated from WT or histidine decarboxylase (HDC) KO mice were sensitized with anti-trinitrophenol (TNP)-immunoglobulin E and then stimulated with TNP-OVA or control OVA. The concentration of histamine released into culture medium is shown (mean ± SEM, n = 3). u.d., undetected (B) Mast cell-deficient KitW-sh/W-sh mice were infested once or twice with ticks. The relative tick repletion is shown (mean ± SEM, n = 3 each), in that the value in the first infestation was defined as 100%. (C) BMMCs prepared from WT or HDC KO mice were intradermally administered into the right flank of KitW-sh/W-sh mice. One group (first) of the recipient mice were infested once with tick larvae on the BMMC-injected site 6 weeks after the transplantation. The other group (second) was infested twice with larvae, first on the left flank 4 weeks after the BMMC transplantation, and 2 weeks later, re-infected with larvae on the BMMC-injected site of the right flank. The relative tick repletion in each group is shown, in that the value in the first infestation was defined as 100% (mean ± SEM, n = 3–4). (D) Mcpt8DTR mice were infested once (first) or twice (second) with tick larvae. To deplete basophils during the second infestation, they were treated with intravenous injection of diphtheria toxin (DT) 1 day before the second infestation. To reconstitute basophils, basophils isolated from tick-infested WT or HDC KO mice were adoptively transferred to the DT-treated mice 2 h before the second infestation. The relative tick repletion in each experimental group is shown (mean ± SEM, n = 3), in that the value in the first infestation of untreated mice was defined as 100%. All the data shown are representative of at least three independent experiments. Statistics: t-test in (A–C) and one-way ANOVA in (D). N.S., not significant; *p < 0.05; **p < 0.01; ***p < 0.001.