●Nature Insight: Infection and immunity.Nature 8 July (2004). Four review articles in this Insight address host immune responses in the face of emerging and re-emerging infectious diseases: The challenge of emerging and re-emerging infectious diseases. Morens, D. M., Folkers, G. K. & Fauci, A. S. Frontal and stealth attack strategies in microbial pathogenesis. Merrell, D. S. & Falkow, S. Inferences, questions and possibilities in Toll-like receptor signalling. Beutler, B. and Translating cell biology in vitro to immunity in vivo. Boes, M. & Ploegh, H. L. (Scanning electron micrograph by A. Ozinsky and A. Aderem, Institute for Systems Biology, Seattle, USA.)

●When the immune system goes on the attack. Brower, V. EMBO reports August (2004) This Science and Society article discusses recent research that hopes to quash concerns over the tardiness of diagnosis of autoimmune disease and the varying effectiveness of current therapies.

●Chemotaxis: signalling the way forward. Van Haastert, P. J. M. & Devreotes, P. N. Nature Reviews Molecular Cell Biology August (2004) In the special focus issue on cytoskeletal dynamics of this month's Nature Reviews Molecular Cell Biology, this review article discusses the processes that mediate random locomotion versus chemotaxis of human neutrophils and Dictyostelium discoideum amoebae, and dissects the key signalling pathways that are involved in these processes.

●Self help for T cells. Hailman, E. & Allen, P. M. Nature Immunology August (2004) The precise components involved in the generation of sustained T-cell receptor (TCR) signals in vivo are uncertain. This News and Views piece reports on the recent data generated using mathematical models and imaging experiments that indicate a key role for CD4 and self-peptides in sustained TCR signalling. Specifically, this model predicts that agonist and endogenous peptides recognized by a TCR pseudodimer might cooperate to enhance the generation of TCR signals.

●MALT lymphoma: from morphology to molecules. Isaacson, P. G. & Du, M.-Q. Nature Reviews Cancer August (2004) This Timeline article chronicles the immunological and molecular developments in our understanding of mucosa-associated lymphoid tissue (MALT) lymphoma, and it describes the contribution of bacterial infection and auto-antigen stimulation to disease pathogenesis.

●Cannabinoids cool the intestine. Kunos, G. & Pacher, P. Nature Medicine July (2004) In this News and Views article, the authors discuss a recent report indicating that stimulation of cannabinoid receptors protects against colonic inflammation, and they suggest that drugs targeting the endogenous cannabinoid system could be used to treat inflammatory bowel disease.