Innate Immunity

Dectin-1 mediates the biological effects of β-glucans. Brown, G. D. et al. J. Exp. Med. 197, 1119–1124 (2003)

Collaborative induction of inflammatory responses by dectin-1 and toll-like receptor 2. Gantner, B. N. et al. J. Exp. Med. 197, 1107–1117 (2003)

Dectin-1 — a recently identified receptor for fungus-derived β-glucan — is a transmembrane receptor that contains an extracellular lectin-like carbohydrate-recognition domain and an immunoreceptor tyrosine-based activation motif (ITAM) in its cytoplasmic tail. It is highly expressed by macrophages and neutrophils, and is also expressed by dendritic cells and some T cells. These two studies now show that dectin-1 collaborates with Toll-like receptors (TLRs) in the recognition of microorganisms. Signalling through dectin-1 results in phosphorylation of the ITAM and leads to phagocytosis and the production of reactive oxygen species, and TLR engagement leads to the production of pro-inflammatory cytokines. Simultaneous engagement of both receptors produces a synergistic effect. These results show that inflammatory responses to microorganisms result from collaborative recognition of distinct microbial components.

Autoimmunity

Immunoregulation of a viral model of multiple sclerosis using the synthetic cannabinoid R(+)WIN55,212. Croxford, J. L. & Miller, S. D. J. Clin. Invest. 111, 1231–1240 (2003)

Some patients suffering from multiple sclerosis (MS) use cannabis to alleviate symptoms of the disease, and several studies are on-going to investigate the basis of these effects. In this study, the immunoregulatory effects of a synthetic cannabinoid-receptor agonist were examined using Theiler's mouse encephalitis virus-induced demyelinating disease — a T helper 1 (TH1)-mediated disease — as a model of MS. Treatment with the agonist at various timepoints inhibited progression of the clinical disease. This was associated with a reduced capacity to generate TH1 cells and down-regulated TH1-cell effector function.

T-cell Development

In vitro generation of T lymphocytes from embryonic stem cell-derived pre-hematopoietic progenitors. de Pooter, R. F. et al. Blood 8 May 2003 (DOI: 10.1182/blood-2003-01-0224)

Embryonic stem (ES) cells can differentiate into all lineages of blood cells in vivo, and are useful tools for studying haematopoiesis in vitro. Although ES cell-derived precursors have been shown to develop into B cells and natural killer cells in vitro, their T-cell potential has not yet been shown. Here, an early ES cell-derived population of Flk1+CD45− pre-haematopoietic precursors that can generate T cells in vitro was defined, which should aid future in vitro studies of T-cell commitment and differentiation.