Leukocytes on Border Patrol

Science's STKE  07 Aug 2007:
Vol. 2007, Issue 398, pp. tw285
DOI: 10.1126/stke.3982007tw285

Immune cells move between the circulation system and tissues in response to infection. Upon detection of inflammation, leukocytes initiate a highly orchestrated sequence of events, whereby they attach and roll along on the surface of the endothelium before squeezing through to the underlying tissue. Auffray et al. reveal a quite distinct type of behavior displayed by a population of monocytes that remain attached to the endothelium in the absence of inflammation. The resident cells appeared to survey the surface of postcapillary venules, veins, and arteries, depending on specific chemokine and integrin signals. Upon detection of inflammatory cues, the cells move into infected sites, where they undergo differentiation into macrophages. Mueller et al. reveal how the down-regulation of chemokines in the lymph node prevents T lymphocytes from entering during an ongoing immune response. This delay may help to optimize the lymph node environment to produce the most effective immune response.

C. Auffray, D. Fogg, M. Garfa, G. Elain, O. Join-Lambert, S. Kayal, S. Sarnacki, A. Cumano, G. Lauvau, F. Geissmann, Monitoring of blood vessels and tissues by a population of monocytes with patrolling behavior. Science 317, 666-670 (2007). [Abstract] [Full Text]

S. N. Mueller, K. A. Hosiawa-Meagher, B. T. Konieczny, B. M. Sullivan, M. F. Bachmann, R. M. Locksley, R. Ahmed, M. Matloubian, Regulation of homeostatic chemokine expression and cell trafficking during immune responses. Science 317, 670-674 (2007). [Abstract] [Full Text]