Credit: Photograph by Daniel Jones

●An inflammatory link. Balkwill, F. & Coussens, L. M. Nature 23 September (2004) This News and Views article discusses the recent data indicating that nuclear factor-κB signalling, which is crucial for inflammatory responses against pathogens, might also activate signalling pathways in cancer cells and tumour-associated inflammatory cells, and promote their malignancy.

●Molecular mechanisms of caspase regulation during apoptosis. Riedl, S. J. & Shi, Y. Nature Reviews Molecular Cell Biology November (2004)

●Inside sensors detecting outside pathogens. De Gregorio, E. & Rappuoli, R. Nature Immunology November (2004) New data discussed in this News and Views article indicate that, in addition to sensing of intracellular bacteria, cytoplasmic NOD (nucleotide-binding oligomerization domain) proteins detect extracellular bacteria following the delivery of peptidoglycan fragments into the cell by a type IV secretion system. This might be another mechanism that allows discrimination between pathogenic and commensal bacteria.

●A license to remember. Ashton-Rickardt, P. G. Nature Immunology November (2004) How CD4+ T cells provide help for the generation of primary and memory CD8+ T-cell responses has been much debated. A new model described in this News and Views article proposes that dendritic cells (DCs) only prime the differentiation of CD8+ T cells into effector and memory cells after CD4+ T cells have 'licensed' them to do so. Licensing of DCs by CD4+ T cells involves the recognition of peptide–MHC complexes on the same DC by CD4+ and CD8+ T cells.

●The nature of stem cells: state rather than entity. Zipori, D. Nature Reviews Genetics November (2004) This Opinion article proposes that the self-renewal and pluripotent capabilities of stem cells are not due to selective expression of specific genes. Instead, 'stemness' is a transient state that can be assumed by any cell.

●Can nicotine treat sepsis? Matthay, M. A. & Ware, L. B. Nature Medicine November (2004)

●Transplantation tolerance: babies take the first step. Odhrai, J. S. & Lakkis, F. G. Nature Medicine November (2004) In adults, pre-formed IgM specific for mismatched blood-group antigens causes hyperacute rejection of heart transplants. However, a new study discussed in this News and Views article shows that babies can tolerate transplants owing to deletion of allograft-reactive B cells.