Figure 6.

Contribution of natural killer (NK) cells to dendritic cell (DC) -mediated vaccination against Leishmania major. (a) Lesion development in mice infected with L. major after vaccination with conditioned bone-marrow-derived dendritic cells (BMDC) in the absence or presence of NK cells during the vaccination phase. NK cells were depleted by two intravenous (i.v.) injections of anti-asialo-serum. Mice were subsequently immunized i.v. with 5 × 10⁵ BMDC conditioned in vitro with L. major lysate and CpG oligodeoxynucleotides (ODN) and were challenged with 2 × 10⁵ L. major promastigotes 14 days later. Control mice were mock-treated with phosphate-buffered saline (PBS) or received only anti-asialo antiserum without BMDC. The increase in size of the infected compared with the non-infected footpad was measured weekly. Each symbol represents the mean ± SD of a minimum of four animals. Where error bars are not visible the bars lie within the confines of the symbol. Differences between the groups are significant (*P < 0.05). (b) Log numbers of average radiance in photons per second per cm² per steradian (p/s/cm²/sr) of luciferase-transgenic L. major parasites in the footpads of infected mice after vaccination with conditioned BMDC with or without NK-cell depletion during the vaccination phase. Better protection results in lower bioluminescence because of lower numbers of parasites in the infected footpad. Parasite burden was determined 6 weeks after challenge infection with L. major. Each bar represents the mean ± SD of a minimum of three animals. Black bar, mock treatment with PBS only; narrow hatched bar, anti-asialo antiserum without vaccination; open bar, vaccination with BMDC conditioned with L. major lysate plus CpG ODN; wide hatched bar, depletion of NK cells during vaccination by anti-asialo antiserum. The data are representative of two independent experiments.