Analysis of the local immune response induced by Dermatophagoides pteronyssinus (Dp) + amorphous silica particles (SPs). NC/Nga mice were intradermally injected on the ventral side of both ears with Dp alone or Dp plus SPs in PBS on days 1, 3, 5, 7, 9, 11, 13, 16, and 18. At 24 h after the last intradermal injection, the ears were removed and homogenized. The homogenates were centrifuged at 10,000 rpm for 5 min, and the supernatants were collected. The levels of interleukin (IL)-4, IL-5, IL-13, interferon (IFN)-γ, IL-18, and thymic stromal lymphopoietin (TSLP) in the supernatants were examined by ELISA (A, B, and D). A regression analysis of IL-18 was also performed (C). Data are presented as mean ± SE of 4-5 animals per group. The results are representative of two separate experiments. *P < 0.05 vs. Dp group.