t cell targeting by anthrax toxins two faces of the same coint细胞靶向的炭疽毒素一枚硬币的两个面.pdf

Toxins 2011, 3, 660-671; doi:10.3390/toxins3060660 OPEN ACCESS toxins ISSN 2072-6651 /journal/toxins Review T Cell Targeting by Anthrax Toxins: Two Faces of the Same Coin Silvia Rossi Paccani 1,2,* and Cosima T. Baldari 1 1 Department of Evolutionary Biology, University of Siena, Via Aldo Moro 2, 53100 Siena, Italy; E-Mail: baldari@unisi.it 2 Novartis Vaccines, Via Fiorentina 1, 53100 Siena, Italy * Author to whom correspondence should be addressed; E-Mail: rossipaccan2@unisi.it or silvia.rossi_paccani@; Tel.: +39-0577-234396; Fax: +39-0577-234476. Received: 3 May 2011; in revisedform: 3 J une 2011 / Accepted: 7 June 2011 / Published: 20 June 2011 Abstract: Bacillus anthracis , similar to other bacterial pathogens, has evolved effective immune evasion strategies to prolong its survival in the host, thus ensuring the unchecked spread of the infection. This function is subserved by lethal (LT) and edema (ET) toxins, two exotoxins produced by vegetative anthrax bacilli following germination of the spores. The structure of these toxins and the mechanism of cell intoxication are topics covered by other reviews in this issue. Here we shall discuss how B. anthracis uses LT and ET to suppress the immune defenses of the host, focusing on T lymphocytes, the key players in adaptive immunity. We shall also summarize recent findings showing that, depending on its concentration, ET has the ability not only to suppress T cell activation but also