[Anti-tumor effect of Plasmodium yoelii infection on melanoma in mice].

OBJECTIVE: To explore the anti-tumor effect of 17XL strains of Plasmodium yoelii (P.y) infection on melanoma in mice.

METHODS: B16F10 tumor cells were axillarilly injected into the right flank of 20 C57BL/6 mice to establish tumor-bearing mouse models. The next day, the mice were randomly divided into a P.y infection group and control group, 10 mice each group. Each mouse of the P.y infection group was intraperitoneally injected with 1×106 red blood cells including 20% P.y infection red blood cells, and each one of the control group were intraperitoneally injected with 1×106 normal red blood cells of C57BL/6 mice. The time of tumor formation of the mice in the two groups was observed and the tumor volumes were measured.

RESULTS: The time of tumor formation in the P.y infection group［ (11.30 ± 0.21) d］was significantly later than that in the control group ［ (10.40 ± 0.22) d］ ( P < 0.05). From the tumors could be accurately measured to the study end point, both the tumors of mice in the two groups were growing, and the tumor volumes of mice in the P.y infection group were significantly less than those in the control group at each time point (all P < 0.05). The growth rate of tumors in the P.y infection group ［ (71.10 ± 6.29) mm3 /d］ was significantly slower than that in the control group ［ (302.80 ± 49.94) mm3 /d］ ( P < 0.05), and the growth rates of tumors everyday in the P.y infection group were significantly slower than those in the control group (all P < 0.05).

CONCLUSIONS: The P.y infection can delay the occurrence of tumor and inhibit the growth of melanoma.