Figure 3.

LTα^−/− airways display a Th1 phenotype even after a strong Th2 antigen challenge. The lung tissues from B6 and LTα^−/− mice (n = 3–5 per group) were homogenized in PBS containing proteinase inhibitors, and the supernatants were collected by centrifugation. Cytokines from the BAL were measured after a 1-ml flushing of the airways through the trachea. IFN-γ (A) and IL-5 (B) levels were measured by ELISA from the lung lysates (left) and BAL fluids (right). (C and D) B6 and LTα^−/− mice were sensitized i.p. on day 0 with 5 × 10³ inactivated soluble S. mansoni egg antigen (SEA). On day 7, the mice were challenged i.t. with SEA. On day 11, mice were killed, and cytokines from the lung and BAL were analyzed. The lung lysates and BAL fluids of those mice were subjected to ELISA. IFN-γ (C) and IL-5 (D) levels are shown (P < 0.05). Data represent the mean ± SD from a representative experiment. Experiments were repeated four times by different individuals with similar results. For intracellular staining, lung cells (E) and splenocytes (F) were collected and stimulated as described in Materials and Methods. Extracellular staining was performed using anti–CD4-PE, and intracellular staining was performed using either IL-4–allophycocyanin or IFNγ-allophycocyanin.