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Infection and Immunity, March 2001, p. 1454-1462, Vol. 69, No. 3
Department of Microbiology and
Immunology1 and New York State
Diagnostic Laboratory,4 College of Veterinary
Medicine, Cornell University, Ithaca, New York 14853; Servico
de Imunologia, Hospital Universitario Prof. Edgard Santos, Universidade
Federal da Bahia, Bahia, Brazil2; and
Department of Immunology and Infectious Diseases, Research
Institute, Palo Alto Medical Foundation, and Division of Infectious
Diseases and Geographic Medicine, Department of Medicine, Stanford
University School of Medicine, Palo Alto, California
493013
Received 22 August 2000/Returned for modification 11 October
2000/Accepted 30 November 2000
We previously demonstrated that mice concurrently infected with
Schistosoma mansoni and Toxoplasma gondii
undergo accelerated mortality which is preceded by severe liver damage.
Abnormally high levels of serum tumor necrosis factor alpha (TNF-
0019-9567/01/$04.00+0 DOI: 10.1128/IAI.69.3.1454-1462.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.
Interleukin-12 Promotes Pathologic Liver Changes
and Death in Mice Coinfected with Schistosoma mansoni and
Toxoplasma gondii
)
in the dually infected mice suggested a role for this and related
proinflammatory mediators in the pathologic alterations. In order to
evaluate the factors involved in increased inflammatory-mediator
production and mortality, interleukin-12
/
(IL-12
/
) mice were coinfected with S. mansoni and T. gondii, and survival and immune
responses were monitored. These IL-12
/
mice displayed
decreased liver damage and prolonged time to death relative to
wild-type animals also coinfected with these parasites. Relative to the
response of cells from the coinfected wild-type animals, levels of
TNF-
, gamma interferon, and NO produced by splenocytes from
coinfected IL-12
/
mice were reduced, and levels of IL-5
and IL-10 were increased, with the net result that the immune response
of the dually infected IL-12
/
mice was similar to that
of the wild-type mice infected with S. mansoni alone. While
dually infected wild-type animals succumb in the absence of overt
parasitemia, the delayed death in the absence of IL-12 is associated
with relatively uncontrolled T. gondii replication. These
data support the view that S. mansoni-infected mice are
acutely sensitive to infection with T. gondii as a result of their increased hepatic sensitivity to high levels of
proinflammatory cytokines; IL-12 and TNF-
are implicated in this process.
*
Corresponding author. Mailing address: Department of
Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853-6401. Phone: (607) 253-4022. Fax: (607)
253-3384. E-mail: eyd1{at}cornell.edu.
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