Leukocyte integrin Mac-1 promotes acute cardiac allograft rejection

Circulation. 2008 Apr 15;117(15):1997-2008. doi: 10.1161/CIRCULATIONAHA.107.724310. Epub 2008 Mar 31.


Background: In allograft rejection, recipient leukocytes and alloantibodies first target donor endothelial cells. Although the leukocyte integrin Mac-1 (alpha(Mbeta2), CD11b/CD18) facilitates cell-cell interactions among leukocytes and interactions between leukocytes and endothelial cells or platelets, its role in allograft survival and vasculopathy is incompletely defined.

Methods and results: This study examined parenchymal rejection and graft arterial disease after total allomismatched cardiac transplantation (BALB/c donor heart and B6 recipients) in wild-type (WT) and Mac-1-deficient (Mac-1(-/-)) recipients. Recipient Mac-1 deficiency attenuated parenchymal rejection and significantly prolonged cardiac allograft survival from 8.3+/-1.3 days in WT recipient allografts (n=18) to 13.8+/-2.3 days in Mac-1(-/-) recipient allografts (n=6; P<0.0001). Accumulation of neutrophils and macrophages significantly decreased in Mac-1(-/-) compared with WT recipients. Adoptive transfer of WT but not Mac-1(-/-) macrophages to Mac-1(-/-) recipients exacerbated parenchymal rejection and reduced allograft survival; in contrast, adoptive transfer of WT neutrophils did not affect graft survival. Mac-1(-/-) macrophages expressed significantly lower levels of costimulatory molecules both in vivo and in vitro, and mixed lymphocyte reaction using alloantigen-primed Mac-1(-/-) macrophages resulted in significantly lower antigen-presenting function than for WT macrophages. Tumor necrosis factor-alpha production also fell in cultures with Mac-1(-/-) macrophages. Despite attenuation of acute rejection, recipient Mac-1-deficiency did not prevent late graft arterial disease.

Conclusions: These studies demonstrate critical participation of Mac-1 in alloresponses during cellular allograft rejection. These observations establish a molecular target for modulating recipient responses to prolong graft survival.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adoptive Transfer
  • Animals
  • Antigen Presentation / immunology
  • CD8-Positive T-Lymphocytes / immunology
  • Cells, Cultured / immunology
  • Coronary Vessels / pathology
  • Endothelial Cells / cytology
  • Endothelial Cells / immunology
  • Graft Rejection / immunology*
  • Heart Transplantation / immunology*
  • Leukocytes / immunology*
  • Lymphocyte Culture Test, Mixed
  • Macrophage-1 Antigen / genetics
  • Macrophage-1 Antigen / physiology*
  • Macrophages, Peritoneal / immunology
  • Mice
  • Mice, Inbred BALB C
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Neutrophils / immunology
  • Neutrophils / transplantation
  • Transplantation, Heterotopic
  • Transplantation, Homologous / immunology
  • Tumor Necrosis Factor-alpha / biosynthesis


  • Macrophage-1 Antigen
  • Tumor Necrosis Factor-alpha