FIG. 6.

ΔlemA Listeria culture supernatants and heat-killed bacteria target cells for recognition by fMIGWII-specific T cells. Cells were treated with wild-type (wt) or mutant (ΔlemA) L. monocytogenes (Lm) preparations and then used as targets for lysis by fMIGWII-specific T cells (line S172) in a standard ⁵¹Cr release assay. (A) J774 cells were treated with heat-killed (HK) L. monocytogenes for 2 h. (B) EL-4 cells were incubated for 1 h with supernatants from L. monocytogenes cultures. The E:T (effector-to-target cell) ratio indicates the number of T cells added for every target cell in the assay. (C) EL-4 cells were treated for 30 min with supernatants from L. monocytogenes cultures and then added to S172 T cells. The percentage of line S172 cells that were CD8⁺ and secreting IFN-γ was determined by intracellular cytokine staining. Representative data from one of three separate experiments are shown.