Blood-borne donor apoptotic cells are captured and presented to T cells by splenic CD11chi DCs.
A) PKH67-labeled BALB/c apoptotic cells were injected i.v. in B6 mice and the entrapment of blood-borne PKH-67+ (green) apoptotic cell fragments by splenic CD11chi CD45RA− DCs (CD8α+ or CD8α−) and CD11cint CD45RA+ pDCs was analyzed by FACS, 18 h later. B) WT and CD11c-DTR-eGFP B6 mice (both Thy1.2+) were reconstituted with CFSE-labeled 1H3.1 CD4 T cells (Thy1.1+), then treated (or not, control) with DT and injected i.v. with BALB/c apoptotic cells. Injection of DT in CD11c-DTR-eGFP mice deleted selectively CD11chi DCs and spared CD11cint pDCs in the spleen (upper dot plots). In the absence of splenic pDCs, CD11c-DTR-eGFP mice were unable to present BALB/c apoptotic cell-derived allopeptides and induce proliferation of the adoptively transferred 1H3.1 CD4 T cells, evaluated 48 h later by CFSE-dilution by FACS-analysis (bottom dot plots). One representative out of 5 (in A) and 3 (in B) individual experiments is shown.