How certain immune cells naturally recognize and react to transplanted tissue during rejection

Monocytes and macrophages may recognize allogeneic grafts through innate allorecognition mechanisms involving the molecule signal regulatory protein α (SIRPα).

• Monocytes and macrophages are known to recognize microbial products and danger signals.
• They may also respond directly to allogeneic grafts, leading to graft rejection.
• Recent evidence suggests these immune cells can mediate graft rejection through direct cell damage and activation of alloreactive T cells.
• The recognition mechanism involves detecting the polymorphic molecule SIRPα on donor cells.
• Understanding this innate allorecognition could enhance knowledge of allograft rejection.

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