The α₁β₁ and α_Eβ ₇ Integrins Define a Subset of Dendritic Cells in Peripheral Lymph Nodes with Unique Adhesive and Antigen Uptake Properties

Dendritic cells (DCs) are a heterogeneous population of APCs with critical roles in T cell activation and immune regulation. We report in this study the identification and characterization of a novel subset of DCs resident in skin-draining peripheral lymph nodes of normal mice. This subset of CD11c _highCD40^highCD8α^{intermediate (int)} DCs expresses the collagen-binding integrin, α₁β₁ and the E-cadherin-binding integrin, α_Eβ₇. Although α₁β₁ and α_Eβ ₇ are also expressed on CD11c^highCD40 ^intCD8α^high lymphoid DCs, CD11c ^highCD40^highCD8α^int DCs demonstrate preferential integrin-mediated adhesion to collagen and fibronectin. This DC subset most likely acquires expression of these integrins in peripheral lymph node, as this subset is not found in the spleen or mesenteric lymph node, and recent DC migrants from the skin lack expression of α₁β ₁ and α_Eβ₇ integrins. Resident CD40^high DCs express α₁β₁ integrin and colocalize with collagen in lymph nodes. When compared with CD11c ^highCD40^highCD8α^int DCs lacking expression of these integrins, the α₁β₁ ⁺α_Eβ₇⁺ DC subset exhibits more efficient formation of Ag-independent conjugates with T cells, and a decreased ability to acquire soluble Ag. Thus, the α ₁β₁ and α_Eβ₇ integrins define a unique population of peripheral lymph node-derived DCs with altered functional properties and adhesive potential that localizes these cells to sites in lymph nodes where Ag presentation to T cells occurs.