Disodium cromoglycate may act as a novel adjuvant for UV-attenuated Toxoplasma gondii vaccine in mouse model

We have proven the beneficial effects during acute Toxoplasma gondii infection when mast cells were inhibited by disodium cromoglycate (DSCG). Here we investigated the adjuvant effect of DSCG on the protective efficacy of UV-attenuated T. gondii (UV-Tg) vaccine. Mice were infected with 102Tg alone or infected with 102Tg plus DSCG (Tg + DSCG), immunized with 105 UV-Tg and challenged with 102Tg (UV-Tg + Tg) or immunized with 105 UV-Tg plus DSCG and challenged with 102Tg (UV-Tg + DSCG + Tg). Compared to Tg group, Tg + DSCG, UV-Tg + Tg, and UV-Tg + DSCG + Tg showed significantly prolonged survival times, decreased parasite burdens, reduced liver histopathologies, and increased levels of Th1 and Th2 cytokines and IL-17 in the livers and spleens by using quantitative real-time reverse transcription-polymerase chain reaction (qRT-PCR). Compared to UV-Tg + Tg, UV-Tg + DSCG + Tg had significantly longer survival time, lower tissue parasite burden and histopathological score, and higher levels of Th1 and Th2 cytokines and IL-17 in the livers or spleens. Our data suggest that DSCG may play an adjuvant role in the immunization induced by UV-attenuated T. gondii in mice, by promoting cellular immune response against T. gondii challenge.