Complement Activation by Giardia duodenalis Parasites through the Lectin Pathway Contributes to Mast Cell Responses and Parasite Control

Infect Immun. 2016 Mar 24;84(4):1092-1099. doi: 10.1128/IAI.00074-16. Print 2016 Apr.


Infection with Giardia duodenalis is one of the most common causes of diarrheal disease in the world. While numerous studies have identified important contributions of adaptive immune responses to parasite control, much less work has examined innate immunity and its connections to the adaptive response during this infection. We explored the role of complement in immunity to Giardia using mice deficient in mannose-binding lectin (Mbl2) or complement factor 3a receptor (C3aR). Both strains exhibited delayed clearance of parasites and a reduced ability to recruit mast cells in the intestinal submucosa. C3aR-deficient mice had normal production of antiparasite IgA, butex vivo T cell recall responses were impaired. These data suggest that complement is a key factor in the innate recognition of Giardia and that recruitment of mast cells and activation of T cell immunity through C3a are important for parasite control.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Complement Pathway, Mannose-Binding Lectin / physiology*
  • Giardia lamblia / physiology*
  • Giardiasis / immunology*
  • Immunoglobulin A / metabolism
  • Mannose-Binding Lectin / genetics
  • Mannose-Binding Lectin / metabolism
  • Mast Cells / physiology
  • Mice
  • Mice, Inbred BALB C
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Protein Array Analysis
  • Receptors, Complement / metabolism
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Signal Transduction / physiology
  • Specific Pathogen-Free Organisms
  • T-Lymphocytes / physiology


  • Immunoglobulin A
  • Mannose-Binding Lectin
  • Mbl2 protein, mouse
  • Receptors, Complement
  • Recombinant Proteins
  • complement C3a receptor