Delivery of a Th1-type immunogen to lung favors priming for Th2 responses. C57BL/6 mice were given an intranasal (IN) delivery of 10⁷L. major or a subcutaneous (SQ) delivery of 5 × 10⁶ parasites into each hind foot. Both groups were challenged 28 days later with an intranasal dose of 10⁷L. major to induce effector responses. Four days after challenge, the mice were sacrificed and their BAL cells recovered, followed by perfusion with PBS and isolation of lung tissue. (a) Cytospins were prepared from BAL cells recovered from individual mice. Bar graph shows the mean (± SE) proportions of lymphocytes (LYMPHs), neutrophils (NEUTs), and eosinophils (EOs) recovered from BAL of individual (n = 4) intranasally or subcutaneously primed mice. Macrophages make up the remaining percentage of cells recovered by BAL and have been omitted for clarity. (b) Lung tissue cells from pooled mice from each group were isolated by collagenase/DNase treatment and set up in culture with varying doses of L. major soluble lysate and splenic APCs to induce antigen-specific cytokine production. Bar graphs show the mean IFN-γ, IL-4, and IL-5 production of duplicate ELISA wells after 4 days of culture.