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Detection of Cytokine Gene Expression in Schistosoma mansoni Vaccine Model by In Situ Hybridization Technique.

1Afifi SS, 2Hegazi F, 2El-Refaei MM, 1Ashour MS and 2El-Sheikh N.

Microbiology Departments, 1Faculty of Pharmacy and 2Faculty of Medicine for Girls, Al-Azhar University, Cairo, Egypt.

An ultra-violet attenuated Schistosoma mansoni cercariae vaccine model was used to study the kinetics of cytokine production during lung and liver phases of immune responses to vaccination and challenge. interleukin-2 (IL-2), Interferon gamma (IFN-g ) and Interleukin-4 (IL-4) were detected by in situ hybridization technique (ISH), using digoxigenin-labeled RNA probes, and quantitated by image analyzer. Significant elevation in the expression of the three cytokines after the second vaccination dose (p< 0.001) was demonstrated in the lung. The peaking time was day 6 for IL-2 mRNA, day 10 for IFN-g mRNA and day 21 for IL-4 mRNA. Following challenge with normal parasites, the expression of IFN-g mRNA increased significantly in the vaccinated/challenged (VC) as compared to naive/challenged (NC) mice groups (p<0.001). Liver analysis at 8 weeks after challenge revealed positive expression of the three cytokines in granuloma areas. The intensity of expression (%) for IL-2 mRNA, IFN-g mRNA and IL-4 mRNA was 26.6 + 1.0, 18.7 + 0.8 and 21.5 + 0.8 in the (VC) as compared to 20.7 + 0.9, 12.4 + 0.5 and 16.4 + 0.7 in the (NC) mice groups respectively (p<0.001). It is concluded that vaccination enhances the expression of Th1 and Th2 cytokines during both pulmonary and liver phases of immune responses to the schistosome, and that quantitative analysis of cytokine mRNA expression using image analyzer increases the usefulness of the ISH technique.