Dendritic cells in human renal inflammation--Part II.

Dendritic cells (DCs) are bone marrow-derived professional antigen-presenting cells that act as master regulators of acquired and innate immune responses. Here, we review the available information on their role in human renal inflammation. In the 1980s and early 1990s, major histocompatibility complex class II antigen- (HLA-DR) positive DCs were first described in normal human kidneys and in the interstitium of kidneys from patients with glomerulonephritis. Several DC subtypes were subsequently distinguished based on their expression of CD1c/BDCA-1, CD141/BDCA-3 and CD209/DC-SIGN (in combination with HLA-DR). These cells were almost exclusively found in the tubulointerstitium, with increased numbers seen during glomerulonephritis. It appears that the human renal tubulointerstitium harbors different DC types which allow the collection of both exogenous as well as endogenous antigens. Plasmacytoid DCs have a plasma cell-like morphology and were commonly found within nodular tubulointerstitial infiltrates. Follicular DCs are rarely seen, but show a predominant localization in organized infiltrates. CD207/langerin is a marker for Langerhans cells. Langerin-positive cells have been found in association with the collecting ducts and urothelium. A functional characterization of these subtypes has been hampered by the difficulty of obtaining samples for analysis. However, these studies are clearly required to define the role of DCs and DC subsets in the pathophysiology of renal disease.