Estradiol-induced impairment of Th1 responses in vivo.
To assess the immunosuppressive function of estradiol in vivo , the administration of estradiol was performed using 5 BLV-infected cattle (animals #6–#10, Figure 4 and Supplemental Figure 4). We confirmed that the concentrations of estradiol in sera were increased by estradiol administration (Figure 4a). PGE2concentrations in sera from these infected cattle were significantly increased for 3 days after estradiol administration (Figure 4b). By contrast, IFN-γ production from whole blood cells stimulated with Con A was suppressed by estradiol administration (Figure 4c). Additionally, as shown in figure 4d, BLV-specific Th1 responses were also impaired by estradiol administration. These results suggest that estradiol inhibits BLV-specific Th1 responses via PGE2 production in vivo .