image: Glennie et al. show that memory CD4+ T cells (green) in the skin reduce the number of parasites after secondary Leishmania infection by recruiting parasite-fighting memory CD4+ T cells (red) circulating in the blood. view more
Credit: The Rockefeller University Press
Immune cells that hang around after parasitic skin infection help ward off secondary attack, according to a study in The Journal of Experimental Medicine. These skin squatters may prove to be the key to successful anti-parasite vaccines.
Leishmania are a group of parasites that are transmitted by sandflies and cause a variety of diseases, including an ulcerative skin disease. Successful clearance of Leishmania infection results in long-lasting immunity to reinfection. This protection relies in part on circulating immune cell called memory CD4+ T cells, which recall the initial infection and respond with increased rapidity and vigor. But the protection provided by transferring these memory cells into uninfected mice pales in comparison to that conferred by prior infection, suggesting the involvement of other cells or pathways.
Phillip Scott and his colleagues at the University of Pennsylvania now show that circulating memory CD4+ T cells rely on a little help from skin-resident friends. The group found that some of the Leishmania-fighting CD4+ T cells that help fend off initial infections in mice linger in the skin for up to a year after the infection resolves. These skin-resident memory cells reduced the number of parasites in the skin during secondary infection, largely due to their ability to attract parasite-fighting memory CD4+ T cells from the blood. Invoking the dual action of skin and blood memory CD4+ T cells may be the key to developing an effective anti-Leishmania vaccine for humans, which has thus far been elusive.
###
Glennie, N.D., et al. 2015. J. Exp. Med. doi:10.1084/jem.20142101
About The Journal of Experimental Medicine
The Journal of Experimental Medicine (JEM) is published by The Rockefeller University Press. All editorial decisions on manuscripts submitted are made by research-active scientists in conjunction with our in-house scientific editors. JEM provides free online access to many article types immediately, with complete archival content freely available online since the journal's inception. Authors retain copyright of their published works and third parties may reuse the content for noncommercial purposes under a creative commons license. For more information, please visit http://www.jem.org .
Journal
Journal of Experimental Medicine