Figure 4.

Interleukin-3 (IL-3) produced by CD4⁺ T cells is responsible for basophil accumulation at the second tick-feeding site. (A) Splenic CD4⁺ T cells isolated from wild-type (WT) or Il3^−/− mice were adoptively transferred into Rag2^−/− mice, and recipient mice were infested twice with ticks. The number of CD4⁺ T cells (left panel) and basophils (right panel) at the second tick-feeding site was examined on day 2 of infestation (mean ± SEM, n = 4 each). (B) WT mice were infested twice with ticks, and the number of IL-3⁺CD4⁺ T cells at the first and second tick-feeding sites (left panel) and the frequency of IL-3⁺ T cells among CD4⁺ T cells at the first and second tick-feeding sites (right panel) were determined (mean ± SEM, n = 3 each). All the data shown are representative of three independent experiments. N.S., not significant; *p < 0.05.