Figure 6.
The KBMA P. aeruginosa immunotherapy stimulates the production of specific lymphocyte CD8+ T cells in vivo and prolongs survival of mice bearing B16-OVA tumor. (a) The average number of spot-forming cells (SFC) per 4 × 105 splenocytes of mice subcutaneous (s.c.) injected with phosphate-buffered saline (PBS), heat-killed (HK) S54-OVA, OSTAB S54-OVA, or KBMA S54-OVA strains at 5 × 106, 5 × 107, 2X 5 × 107, or 4X 5 × 107 bacteria. Mice were s.c. injected on day 14 and 7 in the right flank (1X vaccination), in the right and left flank (2X vaccinations), and in the right and left flanks and the right and left shoulders (4X vaccinations) with 5.107 KBMA S54-OVA bacteria/injection site. ELISpot was used as indicated by the manufacturer. The results presented are the means of three independent experiments. (b–c) C57BL/6J mice received s.c. B16-OVA tumor cells (2 × 105 cells) on day 0. (b) The survival curves of PBS-treated control mice and mice that were prophylactically vaccinated on 14 and 7 days in the right flank with OST S54-OVA (5 × 106), KBMA S54-OVA (5 × 107 in one or two sites of injection), and HK OSTAB S54-OVA (5 × 107). Log-rank test, KBMA S54-OVA 2X versus PBS, P = 0.0006. (c) The survival curves of mice challenged with B16-OVA and vaccinated sixfold (d+1 and every 4 days) with KBMA P. aeruginosa or live strains. Animals were killed when tumor diameters exceeded 10 mm in any dimension for both vaccination schemes. The population size was n = 6 per group. Log-rank test, OSTAB S54-Ei 4X versus OSTAB S54-OVA 4X group, P = 0.0012. KBMA, “killed but metabolically active.”