Protective immunity against Plasmodium berghei malaria after administration of interleukin-12.

Interleukin-12 (IL-12) has been shown to induce protection in mice against Plasmodium cyanomolgi and in rhesus monkey against Plasmodium yeolii. This study is to investigate whether recombinant IL-12 can induce protection in BALB/c mice against Plasmodium berghei. Five mice were given intraperitoneal injection of 7.5 micrograms/kg body weight recombinant mouse IL-12 two days prior to challenge with 5 x 10(4) of P. berghei, while mice in the control group were injected with 0.5 ml of normal saline prior to challenge. In both groups, the parasitaemia appeared on the fourth day after the infection. There was a slight reduction in the parasite burden in mice given IL-12 and the mice also survived longer compared to controls. Statistical significance of the difference could not be determined due to the small sample size. Nevertheless, the results of the study suggested that IL-12 may be able to protect mice against P. berghei infection.