Regulation by Chemokines of Circulating Dendritic Cell Precursors, and the Formation of Portal Tract–Associated Lymphoid Tissue, in a Granulomatous Liver Disease

We have studied the recruitment and roles of distinct dendritic cell (DC) precursors from the circulation into Propionibacterium acnes–induced granulomas in mouse liver. During infection, F4/80⁻B220⁻CD11c⁺ DC precursors appeared in the circulation, migrated into the perisinusoidal space, and matured within newly formed granulomas. Recruited DCs later migrated to the portal area to interact with T cells in what we term “portal tract–associated lymphoid tissue” (PALT). Macrophage inflammatory protein 1α attracted blood DC precursors to the sinusoidal granuloma, whereas secondary lymphoid organ chemokine (SLC) attracted mature DCs to the newly identified PALT. Anti-SLC antibody diminished PALT expansion while exacerbating granuloma formation. Therefore, circulating DC precursors can migrate into a solid organ like liver, and participate in the granulomatous reaction in response to specific chemokines.