β2 Integrins As Regulators of Dendritic Cell, Monocyte, and Macrophage Function

Emerging evidence suggests that the beta(2) integrin family of adhesion molecules have an important role in suppressing immune activation and inflammation. beta(2) integrins are important adhesion and signaling molecules that are exclusively expressed on leukocytes. The four beta(2) integrins (CD11a, CD11b, CD11c, and CD11d paired with the beta(2) chain CD18) play important roles in regulating three key aspects of immune cell function: recruitment to sites of inflammation; cell-cell contact formation; and downstream effects on cellular signaling. Through these three processes, beta(2) integrins both contribute to and regulate immune responses. This review explores the pro- and anti-inflammatory effects of beta(2) integrins in monocytes, macrophages, and dendritic cells and how they influence the outcome of immune responses. We furthermore discuss how imbalances in beta(2) integrin function can have far-reaching effects on mounting appropriate immune responses, potentially influencing the development and progression of autoimmune and inflammatory diseases. Therapeutic targeting of beta(2) integrins, therefore, holds enormous potential in exploring treatment options for a variety of inflammatory conditions.