L. major-infected DM−/− APC fail to display the immunodominant epitope LACK 158–173. Bone marrow DC, prepared from 1 × 106 BM cells as described before (28) and in Materials and Methods, were infected with 35 × 106 L. major promastigotes for 24 h. Infected and uninfected DC were washed and used at various concentrations with the T cell hybridoma (LMR 16.2) specific for LACK 158–173. The data are depicted as IL-2 release, a measure of activation of the T cell hybridoma, and are representative of three to five experiments. Peptide 158–173 (1 µM) was exogenously added in the data shown in the insets. Open symbols represent uninfected and closed symbols represent infected BMDC: Wild-type (●, ○), DM−/− (■, □), Ii−/− (▲, △), and DM−/−Ii−/− (▼, ▽).