Figure 1. Listeria monocytogenes polar lipids activate diverse but not invariant NKT hybridomas.
Polar lipids derived from the bacterium Listeria monocytogenes were incubated at various concentrations in triplicate with a panel of NKT cell hybridomas in the presence of RAW 264.7 cells (RAW, gray circles) or RAW cells stably transfected with CD1d (RAW-CD1d, black circles). Hybridomas were also co-cultured with RAW or RAW-CD1d cells without adding exogenous lipid in duplicate (gray and black asterisks). After 16–18 h of co-culture, supernatants were assayed for the presence of IL-2 by ELISA. Each graph is presented as mean ± SEM and is representative of four (A, B, C), three (C, D, E, F, G, J) or two (H, I) independent experiments.