Characterisation of Plasmodium falciparum macrophage migration inhibitory factor homologue

Abstract

Background Macrophage migration inhibitory factor (MIF), one of the first cytokines described, has a broad range of pro-inflammatory properties. The genome sequencing project of Plasmodium falciparum identified a parasite homologue of MIF. The protein is expressed during asexual bloodstages of the parasite lifecycle that cause malarial disease. The identification of a parasite homologue of MIF raised the question whether it affects monocyte function in a similar manner to its human counterpart. Methods Recombinant P. falciparum MIF (PfMIF) was generated and used in vitro to assess its influence on monocyte function. Antibodies generated against PfMIF were used to determine the expression profile and localisation of the protein in bloodstage parasites. Antibody responses to PfMIF were determined in Kenyan children with acute malaria and controls. Results PfMIF protein was expressed in asexual bloodstage parasites, localised to the Maurer’s cleft. In vitro treatment of monocytes with PfMIF inhibited random migration and reduced the surface expression of toll like receptor (TLR) 2, TLR4 and CD86. Conclusions These results indicate that PfMIF is released during bloodstage malaria and potentially modulates the function of monocytes during acute P. falciparum infection.