title: The divergent roles of macrophages in solid organ transplantation.
abstract: OBJECTIVE
  This review summarizes the phenotype and function of macrophages in the context of solid organ transplantation and will focus on fundamental insights into their paradoxical pro-inflammatory versus suppressive function. We will also discuss the therapeutic potential of regulatory macrophages in tolerance induction.
  
  
  RESULTS
  Macrophages are emerging as an essential element of solid organ transplantation. Macrophages are involved in the pathogenesis of ischemia reperfusion injury, as well as both acute and chronic rejection, exacerbating injury through secretion of inflammatory effectors and by amplifying adaptive immune responses. Notably, not all responses associated with macrophages are deleterious to the graft, and graft protection can in fact be conferred by macrophages. This has been attributed to the presence of macrophages with tissue-repair capabilities, as well as the effects of regulatory macrophages.
  
  
  CONCLUSIONS
  The explosion of new information on the role of macrophages in solid organ transplantation has opened up new avenues of research and the possibility of therapeutic intervention. However, the role of myeloid cells in graft rejection, resolution of rejection and tissue repair remains poorly understood. A better understanding of plasticity and regulation of monocyte polarization is vital for the development of new therapies for the treatment of acute and chronic transplant rejection.
authors.affiliation: aDepartment of Pathology and Laboratory Medicine bUCLA Immunogenetics Center, Department of Pathology and Laboratory Medicine, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, California, USA.
authors.forename: Sahar
authors.initials: S
authors.lastname: Salehi
authors.forename: Elaine F
authors.initials: EF
authors.lastname: Reed
mesh_terms: D056704:Adaptive Immunity; D000818:Animals; D006084:Graft Rejection / Q000276:immunology; D006801:Humans; D008264:Macrophages / Q000276:immunology*; D022423:Myeloid Cells / Q000276:immunology; D016377:Organ Transplantation; D015427:Reperfusion Injury / Q000276:immunology