Ag-specific CD4 T cells promote innate immune responses in liver ischemia reperfusion injury

Our previous studies have documented the unique enrichment of activated CD4 T cells in the liver.Blocking de novo T cell activation did not interfere with their function in ischemia reperfusion injury(IRI).1 We also demonstrated that the CD154-CD40 pathway,but not IFN-γ,was critical for IRI in the liver.Interestingly,alloimmune-primed hosts had significantly more severe IRI in their own livers,which was mediated mainly by CD4 T cells.2 These data prompted us to propose that pre-existing activated CD4 T cells in a host participate in the liver innate immune response against IRI.However,whether these activated/memory T cells require Ag stimulation to function in liver IRI remains unclear.In this report,we addressed this question by utilizing OT II(RAG−/−)T cell receptor transgenic CD4 T cells in a murine liver IRI model.