TH1 CYTOKINE MESSENGER-RNA EXPRESSION DOMINATES IN THE SKIN-DRAINING LYMPH-NODES OF C57BL 6 MICE FOLLOWING VACCINATION WITH IRRADIATED SCHISTOSOMA-MANSONI CERCARIAE, BUT IS DOWN-REGULATED UPON CHALLENGE INFECTION/

Vaccination of C57BL/6 mice with irradiated cercariae of Schistosoma m ansoni results in the induction of high levels of immunity to subseque nt infection. The events occurring in the lymph nodes draining the exp osure site have been analysed ex vivo by reverse transcription-polymer ase chain reaction (RT-PCR) and the timing of cytokine gene expression following exposure has been established. After vaccination, spatial s eparation of the T-helper type 1 (Th1) and Th2 responses was evident, with interferon-gamma (IFN-gamma), interleukin-2 (IL-2) and IL-12 mRNA peaking earlier than mRNA for IL-4, IL-5 and IL-10. In contrast to th e profiles observed post-vaccination, following challenge the IL-4 mRN A was predominant in the draining lymph nodes, with IFN-gamma message levels barely detectable above the naive level. These observations are confirmed by the analysis of IL-4 and IFN-gamma mRNA using competitiv e PCR. From these studies it is clear that irradiated cercariae are mo re able to promote a protective Th1 response, with normal parasites el iciting higher IL-4 and IL-5 expression upon both primary and secondar y stimulation.