The complement inhibitory protein DAF (CD55) suppresses T cell immunity in vivo

Jianuo Liu, Takashi Miwa, Brendan Hilliard, Youhai Chen, John D. Lambris, Andrew D. Wells, Wen Chao Song

Research output: Contribution to journalArticlepeer-review

197 Scopus citations


Decay-accelerating factor ([DAF] CD55) is a glycosylphosphatidylinositol- anchored membrane inhibitor of complement with broad clinical relevance. Here, we establish an additional and unexpected role for DAF in the suppression of adaptive immune responses in vivo. In both C57BL/6 and BALB/c mice, deficiency of the Daf1 gene, which encodes the murine homologue of human DAF, significantly enhanced T cell responses to active immunization. This phenotype was characterized by hypersecretion of interferon (IFN)-γ and interleukin (IL)-2, as well as down-regulation of the inhibitory cytokine IL-10 during antigen restimulation of lymphocytes in vitro. Compared with wild-type mice, Daf1-/- mice also displayed markedly exacerbated disease progression and pathology in a T cell-dependent experimental autoimmune encephalomyelitis (EAE) model. However, disabling the complement system in Daf1-/- mice normalized T cell secretion of IFN-γ and IL-2 and attenuated disease severity in the EAE model. These findings establish a critical link between complement and T cell immunity and have implications for the role of DAF and complement in organ transplantation, tumor evasion, and vaccine development.

Original languageEnglish (US)
Pages (from-to)567-577
Number of pages11
JournalJournal of Experimental Medicine
Issue number4
StatePublished - Feb 21 2005
Externally publishedYes

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology


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