TRAIL-R as a negative regulator of innate immune cell responses,

Muhlenbeck et al., 1998). These discrepancies could high levels of TRAIL upregulation and enhanced cytobe due to differences in cell lines or cell type-specific kine production in TRAIL-R Ϫ/Ϫ cells. The immediatesignaling. However, the similarity to TNF receptor signalearly TLR signaling events in TRAIL-R Ϫ/Ϫ macrophages ing has led to speculation that sensitivity to TRAIL inand dendritic cells are normal, but IB-␣ homeostatic duced apoptosis may be regulated by expression of regulation and NF-B activity at later time points is antiapoptotic factors downstream of NF-B or by more perturbed. These data suggest that TRAIL-R negaproximal factors such as c-FLIP, which inhibits castively regulates innate immune responses. as defects in negative selection, although this latter find- Normal Lymphocyte Populations and Negativ