Immunosuppression in murine malaria: role of activated macrophages.

The role of macrophages in immunosuppression which develops during Plasmodium berghei infection in mice has been studied. The transfer of activated macrophages (or their extracts) from the infected mice with low parasitaemia (less than 10%) to uninfected mice enhanced their humoral response to sheep red blood cells (SRBC) as indicated by the number of splenic IgM and IgG plaque-forming cells (PFC). In contrast, when macrophages obtained during higher parasitaemia (16%) were used, significant inhibition was observed. These findings indicate that during Plasmodium berghei infection in mice macrophages may play a dual role.