Prostaglandins mediate suppression of lymphocyte proliferation and cytokine synthesis in acute Trypanosoma cruzi infection |
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Authors: | Pinge-Filho P Tadokoro C E Abrahamsohn I A |
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Institution: | Center of Biological Sciences, Londrina State University, Londrina, PR, 86051-970, Brazil. |
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Abstract: | Suppression of host lymphoproliferative responses to mitogens and Ag is characteristically seen during acute infection with the protozoan parasite Trypanosoma cruzi. We investigated the reciprocal regulation of prostaglandins (PG), TNF-alpha, and nitric oxide (NO) production and their effects on cytokine production and lymphoproliferative responses to parasite Ag and to Con A by spleen cells (SC) from T.-cruzi-infected mice. Large amounts of PGE2, TNF-alpha, and NO were produced during infection. TNF-alpha stimulated PG and NO synthesis, while both mediators inhibited TNF-alpha synthesis. Blocking PG also reduced NO synthesis indicating that PG stimulate NO production. Treatment with indomethacin or NMLA stimulated lymphoproliferation on days 6 and 22 of infection; on day 14, when suppression of proliferation and NO production was maximal, combined inhibition of NO and PG production restored parasite Ag specific and Con A proliferative responses. Blocking PG or NO production increased IL-2, IFN-gamma, and TNF-alpha, but not IL-12 production by SC; IL-10 levels were not reduced. Indomethacin-treated infected mice had higher mortality compared to untreated infected animals. The data indicate that PG, together with NO and TNF-alpha, participate in a complex circuit that controls lymphoproliferative and cytokine responses in T. cruzi infection. |
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