Trypanosoma cruzi induces strong IL-12 and IL-18 gene expression in vivo: correlation with interferon-gamma (IFN-gamma) production.
IFN-gamma, produced after infection with Trypanosoma cruzi, has been shown to be crucial in the determination of resistance or susceptibility. We have performed a detailed study on the expression of IFN-gamma and of the IFN-gamma-inducing cytokines IL-12 and IFN-gamma-inducing factor (IGIF)/IL-18 with regard to time course and tissue localization. IFN-gamma was present in high amounts in the serum and in the supernatants of unseparated spleen cells and isolated CD4+ and CD8+ T cells from the spleens of infected mice which were stimulated ex vivo with T. cruzi. Using the in situ hybridization technique we demonstrate that IL-12 p40 messages were expressed in the spleen and increased during infection, correlating with the expression of IFN-gamma transcripts. Furthermore, we show for the first time that the mRNA for the cytokine IL-18 was induced by a parasitic infection and that this expression increased during infection with T. cruzi. Interestingly, the message for IL-18 was produced earlier during infection and already had declined until day 38, when IFN-gamma and IL-12 p40 transcripts were optimally expressed. Surprisingly, the changes in IL-12 and IL-18 mRNA production were clearly seen only by in situ hybridization, but less clearly by quantitative reverse-transcriptase polymerase chain reaction (RT-PCR). This is possibly due to the extensive activation and proliferation of spleen cells observed during infection leading to a dilution of these specific mRNAs.
Meyer Zum Büschenfelde
C
C
Bernhard Nocht-Institute for Tropical Medicine, Department of Immunology, Hamburg, Germany.
Cramer
S
S
Trumpfheller
C
C
Fleischer
B
B
Frosch
S
S
D000818:Animals; D002478:Cells, Cultured; D014355:Chagas Disease / Q000276:immunology*; D016207:Cytokines / Q000235:genetics*; D007371:Interferon-gamma / Q000096:biosynthesis*; D018664:Interleukin-12 / Q000235:genetics*; D020382:Interleukin-18; D051379:Mice; D008807:Mice, Inbred BALB C; D012333:RNA, Messenger / Q000032:analysis*
D016207:Cytokines; D020382:Interleukin-18; D012333:RNA, Messenger; D018664:Interleukin-12; D007371:Interferon-gamma