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Infection and Immunity, June 2006, p. 3190-3203, Vol. 74, No. 6
0019-9567/06/$08.00+0     doi:10.1128/IAI.00008-06
Copyright © 2006, American Society for Microbiology. All Rights Reserved.

Involvement of Gonadal Steroids and Gamma Interferon in Sex Differences in Response to Blood-Stage Malaria Infection

Amy Cernetich, Lindsey S. Garver, Anne E. Jedlicka, Pamela W. Klein, Nirbhay Kumar, Alan L. Scott, and Sabra L. Klein^*

W. Harry Feinstone Department of Molecular Microbiology and Immunology, The Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland 21205

Received 3 January 2006/ Returned for modification 11 February 2006/ Accepted 4 March 2006

To examine the hormonal and immunological mechanisms that mediate sex differences in susceptibility to malaria infection, intact and gonadectomized (gdx) C57BL/6 mice were inoculated with Plasmodium chabaudi AS-infected erythrocytes, and the responses to infection were monitored. In addition to reduced mortality, intact females recovered from infection-induced weigh loss and anemia faster than intact males. Expression microarrays and real-time reverse transcription-PCR revealed that gonadally intact females exhibited higher expression of interleukin-10 (IL-10), IL-15R, IL-12Rß, Gadd45, gamma interferon (IFN-), CCL3, CXCL10, CCR5, and several IFN-inducible genes in white blood cells and produced more IFN- than did intact males and gdx females, with these differences being most pronounced during peak parasitemia. Intact females also had higher anti-P. chabaudi immunoglobulin G (IgG) and IgG1 responses than either intact males or gdx females. To further examine the effector mechanisms mediating sex differences in response to P. chabaudi infection, responses to infection were compared among male and female wild-type (WT), T-cell-deficient (TCRß^–/–), B-cell-deficient (µMT), combined T- and B-cell-deficient (RAG1), and IFN- knockout (IFN-^–/–) mice. Males were 3.5 times more likely to die from malaria infection than females, with these differences being most pronounced among TCRß^–/–, µMT, and RAG1 mice. Male mice also exhibited more severe weight loss, anemia, and hypothermia, and higher peak parasitemia than females during infection, with WT, RAG1, TCRß^–/–, and µMT mice exhibiting the most pronounced sexual dimorphism. The absence of IFN- reduced the sex difference in mortality and was more detrimental to females than males. These data suggest that differential transcription and translation of IFN-, that is influenced by estrogens, may mediate sex differences in response to malaria.

Supplemental material for this article may be found at http://iai.asm.org/.

Editor: W. A. Petri, Jr.

Present address: Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, PA 19129.