However, pyriproxyfen at doses of 9 and 15 mM resulted in higher titers of OVA-specific total IgG than in

controls (two- and fivefold greater; P = 0.01 and P = 0.002, Doxorubicin mouse respectively). There were no significant differences in the titers of total IgG immune response between groups treated with 9 and 15 mM pyriproxyfen. These results indicate that OVA-specific total IgG titers increased significantly in a dose-dependent manner. A time-dependent assay was performed to evaluate how long pyriproxyfen remains capable of enhancing the IgG immune response. Groups of 12 mice were immunized with OVA in 5% ethanol or OVA containing alum, according to the above schedule, and pyriproxyfen (15 mM) injected followed by injection of OVA (0.5 μg) at 0, 3 and 24 hrs. Blood samples were collected on Week 8 and subjected to ELISA to detect OVA-specific total IgG immune responses in sera. As shown in Figure 4, when OVA was injected at 0 and 3 hrs after injecting pyriproxyfen, the OVA-specific total IgG titers were significantly higher (threefold) than those of controls

(P = 0.008 and P = 0.006, respectively). Immunization with OVA in alum also resulted in a significantly increased OVA-specific total IgG titer (P = 0.01). As expected, there were no significant differences between the alum, 0 and 3 hr groups. In addition, the differences in total IgG titer between these groups and the control remained insignificant check details in the 24 hr group. In the present study, large

doses of pyriproxyfen (9 or 15 mM) greatly increased total IgG antibody titers, whereas a small dose (3 mM) did not induce a significant increase in this titer (Fig. 3). These results indicate that administration of a small dose of pyriproxyfen has no immune-enhancing effect. The World Health Organization accepts a titer of pyriproxyfen of up to ca. 1 μM (0.3 mg/L) in human drinking water [4]. In the present study, we observed no adverse effects on mice at the largest dose of pyriproxyfen tested, suggesting that pyriproxyfen is safe for mammals. However, administration of a large dose of pyriproxyfen specifically enhanced the total IgG immune response with high antibody titers. Interestingly, this enhancement of total IgG immune response by pyriproxyfen was time-restricted new (Fig. 4). [14C]Pyriproxyfen orally administered to rats is rapidly eliminated from the body within 48 hrs, predominantly in the feces (90%) with 4–11% in the urine [4]. This rapid elimination of pyriproxyfen from the body may explain the time-restricted nature of the enhancement of total IgG immune response by administration of large doses of pyriproxyfen, which may in turn decrease any negative effect of pyriproxyfen on mammalian immune responses. These two characteristics suggest that pyriproxyfen is a safe chemical for enhancing the total IgG immune response in vivo.