Effect of recombinant human colony-stimulating factor on the course of parasitaemia in non-lethal rodent malaria.

The effect of repeated subcutaneous injections of recombinant human granulocyte colony-stimulating factor (rhG-CSF) on the attenuated Plasmodium berghei XAT infection in CBA mice was examined. When mice were injected with rhG-CSF daily beginning 2 days before infection, the neutrophil count in the peripheral blood increased 5 times higher than that of control mice and the development of parasitaemia was suppressed significantly during the early phase of the infection. This suppressive effect of rhG-CSF was reduced by treatment of the mice with either anti-interferon (IFN)-gamma or anti-tumour necrosis factor (TNF)-alpha immunoglobulins. These results suggest that neutrophils may have a role in immunity against the parasites and that IFN-gamma and TNF-alpha are possibly involved.