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Antimicrobial Agents and Chemotherapy, October 1998, p. 2549-2556, Vol. 42, No. 10
Department of Biochemistry and Immunology,
Received 30 December 1997/Returned for modification 27 April
1998/Accepted 16 July 1998
The roles of gamma interferon (IFN-
0066-4804/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
Interleukin-12 Enhances In Vivo Parasiticidal Effect of
Benznidazole during Acute Experimental Infection with a Naturally
Drug-Resistant Strain of Trypanosoma cruzi
) and interleukin-12 (IL-12)
in mediating and/or enhancing the in vivo trypanosomicidal activity of
the nitroheterocyclic derivative benznidazole (Bz) were evaluated
during early stages of experimental Chagas' disease. Our results show
that treatment of Trypanosoma cruzi-infected mice with
anti-cytokine monoclonal antibodies (MAbs) had no apparent effect when
the optimal dose of Bz (100 mg/kg of body weight) was used. In
contrast, treatment with anti-IL-12 or anti-IFN-
MAbs enhanced the
parasitemia and accelerated the mortality of mice treated with a
suboptimal dose of Bz (25 mg/kg). Simultaneous treatment with a
suboptimal dose of Bz and recombinant IL-12 (rIL-12) enhanced the
efficacy of drug treatment in terms of parasitemia and mouse survival.
Interestingly, we found that drug-resistant T. cruzi
strains were found to be poor inducers of IL-12 both in vitro and in
vivo compared to strains of T. cruzi which are susceptible
or partially resistant to Bz treatment. These results suggest that
early activation of the cellular compartment of the immune system by
IL-12 may favor in vivo Bz activity against T. cruzi. In
order to test this hypothesis mice infected with the drug-resistant
Colombiana strain of T. cruzi were treated with 100 mg of
Bz per kg plus different concentrations of rIL-12. By using the results
of PCR and serological and parasitological methods as the criteria of a
cure, our results indicate that a higher percentage of mice treated
with Bz combined with rIL-12 than mice treated with Bz alone are cured.
*
Corresponding author. Mailing address: Laboratory of
Chagas' Disease, Centro de Pesquisas René Rachou, FIOCRUZ, Av.
Augusto de Lima 1715, 30190-002 Belo Horizonte, MG, Brazil. Phone:
55-31-295-3566. Fax: 55-31-295-3115. E-mail:
ritoga{at}mono.icb.ufmg.br.
Antimicrobial Agents and Chemotherapy, October 1998, p. 2549-2556, Vol. 42, No. 10
0066-4804/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
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