Recombinant IsSMase superimposes IL-4 expression potential in CD4 T cells undergoing Th1 differentiation in response to viral immunization. Adoptively transferred CFSE-labeled BALB/c HA-specific TCR transgenic CD4 T cells were recovered 4 days following adoptive transfer into BALB/c recipients that were simultaneously injected intradermally with either soluble HA peptide or viral-HA at the site either infested with 10 nymphs on day -1 or intradermally injected with SGE, IsSMase or PBS (Control, C). A, Representative CFSE-dilution histograms and B, quantitative analysis. C, Representative IFN-γ vs IL-4 intracellular staining plots and D, quantitative analysis of IL-4 intracellular cytokine expression. N=4 for both groups.