Dendritic cells and toll-like receptors 2 and 4 in the ileum of Crohn's disease patients

We investigated myeloid-dendritic cell (DC) marker and Toll-like receptor (TLR)-2 and 4 distributions in ileal samples from Crohn's disease (CD) patients (n = 14) and controls (n = 13). In controls, no TLR-2⁺ cells were observed, and higher numbers of TLR-4⁺ and DC-SIGN⁺ cells (P < 0.01) were detected in ileal samples when compared versus colonic tissues. In non-inflamed CD ileum, TLR-4⁺ and DC-SGN⁺ cells were depleted from superficial areas of the villus, and a significant CD1a⁺ cell infiltration (P < 0.01) was observed when compared to ileal controls and non-inflamed colonic CD samples. In inflamed CD ileum, DC-SIGN⁺, CD1a⁺, TLR-4⁺ and few TLR-4 ⁺DC-SIGN⁺ cells were detected as well as CD83 depletion. No correlation between TLR-2 and DC markers was detected in CD samples. A unique distribution of myeloid-DC markers characterized the CD ileum. Also, the presence of significant amounts of ileal CD1a⁺ cells may provide a relevant DC-mediated mechanism for antigen recognition in the pathogenesis of CD.