Immune evasion of Plasmodium falciparum by RIFIN via inhibitory receptors

Nature. 2017 Dec 7;552(7683):101-105. doi: 10.1038/nature24994. Epub 2017 Nov 29.

Abstract

Malaria is among the most serious infectious diseases affecting humans, accounting for approximately half a million deaths each year. Plasmodium falciparum causes most life-threatening cases of malaria. Acquired immunity to malaria is inefficient, even after repeated exposure to P. falciparum, but the immune regulatory mechanisms used by P. falciparum remain largely unknown. Here we show that P. falciparum uses immune inhibitory receptors to achieve immune evasion. RIFIN proteins are products of a polymorphic multigene family comprising approximately 150-200 genes per parasite genome that are expressed on the surface of infected erythrocytes. We found that a subset of RIFINs binds to either leucocyte immunoglobulin-like receptor B1 (LILRB1) or leucocyte-associated immunoglobulin-like receptor 1 (LAIR1). LILRB1-binding RIFINs inhibit activation of LILRB1-expressing B cells and natural killer (NK) cells. Furthermore, P. falciparum-infected erythrocytes isolated from patients with severe malaria were more likely to interact with LILRB1 than erythrocytes from patients with non-severe malaria, although an extended study with larger sample sizes is required to confirm this finding. Our results suggest that P. falciparum has acquired multiple RIFINs to evade the host immune system by targeting immune inhibitory receptors.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • B-Lymphocytes / immunology
  • B-Lymphocytes / metabolism
  • CHO Cells
  • Cricetulus
  • Erythrocytes / immunology
  • Erythrocytes / parasitology
  • HEK293 Cells
  • Humans
  • Immune Evasion / immunology*
  • Killer Cells, Natural / immunology
  • Killer Cells, Natural / metabolism
  • Leukocyte Immunoglobulin-like Receptor B1 / chemistry
  • Leukocyte Immunoglobulin-like Receptor B1 / immunology*
  • Ligands
  • Malaria, Falciparum / immunology
  • Malaria, Falciparum / parasitology
  • Malaria, Falciparum / pathology
  • Membrane Proteins / genetics
  • Membrane Proteins / immunology*
  • Membrane Proteins / metabolism
  • Plasmodium falciparum / genetics
  • Plasmodium falciparum / immunology*
  • Plasmodium falciparum / metabolism
  • Protozoan Proteins / genetics
  • Protozoan Proteins / immunology*
  • Protozoan Proteins / metabolism
  • Receptors, Immunologic / chemistry
  • Receptors, Immunologic / immunology*
  • Sample Size

Substances

  • Leukocyte Immunoglobulin-like Receptor B1
  • Ligands
  • Membrane Proteins
  • Protozoan Proteins
  • RIFIN protein, Plasmodium falciparum
  • Receptors, Immunologic
  • leukocyte-associated immunoglobulin-like receptor 1