A comparative study of the kinetic changes of hemopoietic stem cells in mice infected with lethal and non-lethal malaria.

The kinetic changes of hemopoietic stem cells in bone marrow and spleen were compared between lethal Plasmodium berghei- and non-lethal P. yoelii 17x-infected mice. P. yoelii 17x-infected mice showed more severe splenomegaly than those infected with P. berghei. P. yoelii 17x-infected mice also showed a greater degree of sustained increase in number of multipotent hemopoietic stem cells (colony-forming units in spleen: CFU-S) and committed stem cells for granulocytes and macrophages (CFU-GM) and for erythrocytes (CFU-E) than P. berghei-infected mice. Such an increase was predominantly seen in the spleen of P. yoelii 17x-infected mice. In P. berghei-infected mice, the number of CFU-S, CFU-GM and also CFU-E only transiently increased and then decreased to a subnormal level at the late stage of infection. The proportion of cycling CFU-S was higher in P. berghei-infected mice than in P. yoelii 17x-infected mice. The IL-3 producing activity per spleen was much higher in P. yoelii 17x-infected than in P. berghei-infected mice at any point in time during the infection. Thus, hemopoietic changes seen after malaria infection seem to be closely related to the pathogenicity of the malaria parasite.