Objective To find out relationship between the in vitro schistosome egg antigen (SEA) stimulated IFN γ and IL 4 mRNA expressions and the in vivo SEA elicited granulomatous responses, the transcriptions of IFN γ and IL 4 gene were investigated in the spleen of BALB/c mice infected with Schistosoma japonicum (S japonicum) Methods Spleens were removed at 0, 3, 5, 8, and 10 and 12 weeks after infection and the spleen cells were incubated in the presence of SEA The extracted RNA was analyzed for IFN γ and IL 4 mRNA by reverse transcription PCR (RT PCR) Newly formed liver granulomas were measured Results The study revealed that no detectable IFN γ and IL 4 mRNA RT PCR products were found in SEA treated spleen cells from uninfected, or 3 week infected mice, whereas IL 4 mRNA was found to be expressed in 5 and 8 week infected mice, and an appreciable enhanced expression of IL 4 mRNA was observed in SEA stimulated spleen cells at 8 week infection than at 5 week infections However, SEA could not induce IFN γ and IL 4 mRNA transcription in 10 and 12 week infected mice, indicating the modulated expression of IFN γ and IL 4 mRNA Conclusion The significant changes of IL 4 mRNA expression in SEA stimulated spleen cells during S japonicum infection were coincident with SEA elicited granuloma formation and modulation in vivo Objective To find out relationship between the in vitro schistosome egg antigen (SEA) stimulated IFN γ and IL 4 mRNA expressions and the in vivo SEA elicited granulomatous responses, the transcriptions of IFN γ and IL 4 gene were investigated in the spleen of BALB / c mice infected with Schistosoma japonicum (S japonicum) Methods Spleens were removed at 0, 3, 5, 8, and 10 and 12 weeks after infection and the spleen cells were incubated in the presence of SEA The extracted RNA was analyzed for IFN γ and IL 4 mRNA by reverse transcription PCR (RT PCR) Newly formed liver granulomas were measured Results The study revealed that no detectable IFN γ and IL 4 mRNA RT PCR products were found in SEA treated spleen cells from uninfected, or 3 weeks infected mice, whereas IL 4 mRNA was found to be expressed in 5 and 8 week infected mice, and an appreciably enhanced expression of IL4 mRNA was observed in SEA stimulated spleen cells at 8 week infection than at 5 week infection However, SEA could not induce IFN [gamma] and IL4 mRNA transcription in 10 and 12 week infected mice, indicating the modulated expression of IFN [gamma] and IL4 mRNA Conclusion The significant changes of IL4 mRNA expression in SEA stimulated spleen cells during S japonicum infection were coincident with SEA elicited granuloma formation and modulation in vivo