Dendritic cells in the pathophysiology of sarcoidal reactions

Dendritic cells play an important role in regulating both normal and pathophysiologic immune responses. Complicating the interpretation of dendritic cell function has been the observation that dendritic cells are not only rare, but can demonstrate multiple maturation/differentiation states. Despite these experimental limitations, the accumulating evidence suggests that dendritic cell are a dynamic migratory population that can be recruited into areas of peripheral inflammation. In the peripheral site of inflammation, dendritic cell function appears to involve the processing of antigen and its subsequent presentation to T lymphocytes. Dendritic cells also appear to be capable of transporting antigen to the regional lymph node through the afferent lymphatics. Dendritic cells can be found in the paracortex where they appear to be interacting with T lymphocytes to provide both membrane-bound and soluble activation signals. The central regulatory role of the dendritic cell in immune responses suggests that sarcoidal reactions, and other mononuclear inflammatory processes, are likely to be clinical entities that reflect perturbed dendritic cell function.