A discrete subpopulation of dendritic cells transports apoptotic intestinal epithelial cells to T cell areas of mesenteric lymph nodes

This study identifies a dendritic cell (DC) subset that constitutively tran sports apoptotic intestinal epithelial cell, remnants to T cell areas of me senteric lymph nodes in vivo. Rat intestinal lymph contains two DC populati ons. Both populations have typical DC morphology, are major histocompatibil ity complex class IIhi, and express OX62, CD11c, and B7. CD4(+)/OX41(+) DCs are strong antigen-presenting cells (APCs). CD4(-)/OX41(-) DCs are weak AP Cs and contain cytoplasmic apoptotic DNA, epithelial cell-restricted cytoke ratins, and nonspecific esterase (NSE)(+) inclusions. not seen in OX41(+) D Cs. Identical patterns of NSE electrophoretic variants exist in CD4(-)/OX41 (-) DCs, intestinal epithelial cells, and mesenteric node DCs but not in ot her DC populations, macrophages, or tissues. Terminal deoxynucleotidyl tran sferase-mediated dUTP-biotin nick-end labeling (TUNEL)-positive DCs and str ongly NSE+ DCs are present in intestinal lamina propria. Peyer's patches an d mesenteric but not other lymph nodes contain many strongly NSE+ DCs in in terfollicular and T cell areas. Similar DCs are seen in the ileum and in T cell areas of mesenteric nodes in gnotobiotic rats. These results show that a distinct DC subset constitutively endocytoses and transports apoptotic c ells to T cell areas and suggest a role for these DCs in inducing and maint aining peripheral self-tolerance.