Immature myeloid and plasmacytoid dendritic cells infiltrate renal tubulointerstitium in patients with lupus nephritis.

Systemic lupus erythematosus (SLE) is an autoimmune disease involving several organs. SLE patients developing lupus nephritis (LN) frequently have the worst outcome. Recent data have shown that dendritic cells (DCs) may have a central role in SLE pathogenesis directing the immune response against auto-antigens. In this study we describe a reduction in circulating BDCA1+ and BDCA3+ myeloid DCs, and BDCA2+ plasmacytoid DCs in patients with active LN compared to those in the remission state. Analysis of LN biopsies revealed a strong tubulo-interstitial infiltrate of BDCA1+, BDCA3+ and BDCA4+ DCs which were negative for DC-LAMP, a specific marker of mature DCs. The extent of the DCs infiltrate was higher in class III/IV LN than in normal kidney. These results show for the first time that three DCs subsets, decreased at circulating levels, are recruited within the kidney, indicating that DCs might play a pathogenic role in SLE patients with nephritis.