Engagement of glycosylphosphatidylinositol-anchored proteins results in enhanced mouse and human invariant natural killer T cell responses

Immunology. 2011 Mar;132(3):361-75. doi: 10.1111/j.1365-2567.2010.03369.x. Epub 2010 Nov 11.


Invariant natural killer T (iNKT) cells are a small subset of lymphocytes that recognize glycolipid antigens in the context of CD1d and consequently produce large quantities of pro-inflammatory and/or anti-inflammatory cytokines. Several transmembrane glycoproteins have been implicated in the co-stimulation of iNKT cell responses. However, whether glycosylphosphatidylinositol (GPI)-anchored proteins can function in this capacity is not known. Here, we demonstrate that antibody-mediated cross-linking of the prototype mouse GPI-anchored protein Thy-1 (CD90) on the surface of a double-negative (CD4⁻CD8⁻) iNKT cell line leads to cytokine production at both the mRNA and protein levels. In addition, Thy-1 triggering enhanced cytokine secretion by iNKT cells that were concomitantly stimulated with α-galactosylceramide (αGC), consistent with a co-stimulatory role for Thy-1 in iNKT cell activation. This was also evident when a CD4+ mouse iNKT cell line or primary hepatic NKT cells were stimulated with αGC and/or anti-Thy-1 antibody. Cross-linking Ly-6A/E, another GPI-anchored protein, could also boost cytokine secretion by αGC-stimulated iNKT cells, suggesting that the observed effects reflect a general property of GPI-anchored proteins. To extend these results from mouse to human cells, we focused on CD55, a GPI-anchored protein that, unlike Thy-1, is expressed on human iNKT cells. Cross-linking CD55 augmented αGC-induced iNKT cell responses as judged by more vigorous proliferation and higher CD69 expression. Collectively, these findings demonstrate for the first time that GPI-anchored proteins are able to co-stimulate CD1d-restricted, glycolipid-reactive iNKT cells in both mice and humans.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Separation
  • Cytokines / biosynthesis
  • Cytokines / immunology
  • Enzyme-Linked Immunosorbent Assay
  • Female
  • Flow Cytometry
  • Glycosylphosphatidylinositols / immunology*
  • Humans
  • Lymphocyte Activation / immunology*
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Natural Killer T-Cells / immunology*
  • Reverse Transcriptase Polymerase Chain Reaction


  • Cytokines
  • Glycosylphosphatidylinositols