Fig. 4.

Suppression of the growth of Renca tumors in mice by intratumoral injection of HVJ-E. a Renca cells were inoculated intradermally into the backs of syngeneic BALB/c mice. Then HVJ-E (open circle) or saline (filled square) (n = 5 per group) was injected three times (on days 5, 10, and 15) into the resulting tumors. Tumor growth was significantly inhibited by HVJ-E injection (*P < 0.01) and approximately 50% of the mice became tumor-free. Data shown are representative of experiments that were repeated five times with similar results. b Kaplan–Meier survival curves for HVJ-E-treated and saline-treated mice. When HVJ-E (open circle) or saline (filled square) (n = 5 per group) was injected three times into the intradermal Renca tumors of BALB/c mice, the survival of HVJ-E-treated mice was significantly better than that of saline-treated mice (*P < 0.01). Data shown are representative of experiments that were repeated four times with similar results. c Loss of the antitumor effect of HVJ-E after neutralization of NK activity. Renca cells were inoculated intradermally into syngeneic BALB/c mice, and then HVJ-E was injected three times into the resulting tumors together with anti-asialo GM1 antibody (filled square) or control IgG (filled circle) (n = 5 per group). Tumor growth was inhibited in the mice treated with HVJ-E plus control IgG, whereas it was not inhibited in mice treated with HVJ-E plus anti-asialo GM1 antibody (*P < 0.05). Data shown are representative of experiments that were repeated three times with similar results. Arrows indicate the timing of injection. SE (<5%). Statistical analysis was done with the unpaired t test (a, c) and the Log-rank test (b)