Figure 3.

Interleukin-3 (IL-3) is necessary and sufficient for basophil accumulation at the tick-feeding site. (A) The transcriptional expression of indicated genes at uninfested skin, first or second tick-feeding site on day 2 of infestation is shown (mean ± SEM, n = 3 each). (B,C) Wild-type, Il4^−/−, or Il3^−/− mice were infested twice with ticks, and the number of basophils (mean ± SEM, n = 4 each) at the second tick-feeding site in each mouse strain was examined on day 2 of infestation. (D) Rag2^−/− mice were treated daily with subcutaneous administration of recombinant IL-3 (100 ng/injection/day) in the right flank and control PBS in the left flank for 10 days from day −7 to day 2, and on day 0, mice were primarily infested with ticks at the administration sites of both flanks. The number of basophils (mean ± SEM, n = 4 each) at the first tick-feeding site of each side of flank was examined on day 2 of infestation. All the data shown are representative of three independent experiments. N.S., not significant; *p < 0.05; ***p < 0.001.