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Infection and Immunity, February 2009, p. 733-738, Vol. 77, No. 2
0019-9567/09/$08.00+0     doi:10.1128/IAI.00202-08
Copyright © 2009, American Society for Microbiology. All Rights Reserved.

In Vitro Activity of Acanthamoeba castellanii on Human Platelets and Erythrocytes{triangledown}

A. Mattana,1* L. Alberti,1 G. Delogu,2 P. L. Fiori,2 and P. Cappuccinelli2

Department of Pharmacological Sciences,1 Department of Biomedical Sciences, Division of Experimental and Clinical Microbiology, University of Sassari, Sassari, Italy2

Received 13 February 2008/ Returned for modification 18 April 2008/ Accepted 6 November 2008

The effect of Acanthamoeba on human platelets and erythrocytes has not been fully elucidated. This paper reports that cell-free supernatants prepared from A. castellanii can activate human platelets, causing both a significant increase in the cytosolic free-calcium concentration and platelet aggregation. In addition, we demonstrated that platelet activation depends on the activity of ADP constitutively secreted into the medium by trophozoites. This study also showed that A. castellanii can affect human red blood cells, causing hemolysis, and provided evidence that hemolysis occurs in both contact-dependent and contact-independent ways; there are differences in kinetics, hemolytic activity, and calcium dependency between the contact-dependent and contact-independent mechanisms. Partial characterization of contact-independent hemolysis indicated that ADP does not affect the plasma membrane permeability of erythrocytes and that heat treatment of amoebic cell-free supernatant abolishes its hemolytic activity. These findings suggest that some heat-labile molecules released by A. castellanii trophozoites are involved in this phenomenon. Finally, our data suggest that human platelets and erythrocytes may be potential cell targets during Acanthamoeba infection.

* Corresponding author. Mailing address: Dipartimento di Scienze del Farmaco, Via Muroni 23/A, 07100 Sassari, Italy. Phone: 39-079-228744. Fax: 39-079-228715. E-mail: dsfanto{at}uniss.it

{triangledown} Published ahead of print on 17 November 2008.

Editor: J. F. Urban, Jr.

Infection and Immunity, February 2009, p. 733-738, Vol. 77, No. 2
0019-9567/09/$08.00+0     doi:10.1128/IAI.00202-08
Copyright © 2009, American Society for Microbiology. All Rights Reserved.





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