IL-4 reduces resistance of mice to Trypanosoma cruzi infection.
The role of IL-4 has often been studied, especially in the Leishmania major infection model, but not in Trypanosoma cruzi infection. In the present study, the role of IL-4 in host defense against infection with the Tulahuen strain of T. cruzi was examined by depleting IL-4 with an anti-IL-4 monoclonal antibody in vivo. In both IL-4 depleted and control C57BL/6 mice, the parasitemia showed peaks on the 21st day of infection. Both parasitemia and mortality were decreased in IL-4 depleted mice compared with control mice when IFN-gamma and nitric oxide productions were increased in IL-4 depleted mice compared with control mice. The mice treated with N-nitro-L-arginine methyl ester, a competitive inhibitor of nitric oxide synthase, showed increased susceptibility to T. cruzi infection to the same level in both IL-4 depleted and control mice. Thus, it is suggested that endogenous IL-4 induces susceptibility to T. cruzi mainly by suppressing the production of IFN-gamma and nitric oxide, which has trypanocidal activity.
Hiyama
K
K
Department of Parasitology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
Hamano
S
S
Nakamura
T
T
Nomoto
K
K
Tada
I
I
D000818:Animals; D000953:Antigens, Protozoan / Q000276:immunology; D014355:Chagas Disease / Q000276:immunology* / Q000401:mortality / Q000469:parasitology; D016207:Cytokines / Q000096:biosynthesis; D015847:Interleukin-4 / Q000096:biosynthesis / Q000276:immunology*; D008213:Lymphocyte Activation; D051379:Mice; D008810:Mice, Inbred C57BL; D009500:Neutralization Tests; D009569:Nitric Oxide / Q000096:biosynthesis; D018512:Parasitemia / Q000276:immunology* / Q000401:mortality / Q000469:parasitology; D014349:Trypanosoma cruzi / Q000276:immunology*
D000953:Antigens, Protozoan; D016207:Cytokines; D015847:Interleukin-4; D009569:Nitric Oxide