The Immunomodulator AS101 Restores TH1Type of Response Suppressed byBabesia rodhainiin BALB/c Mice

Abstract The immunomodulator AS101 has been previously shown to confer protection upon BALB/c mice infected with the intraerythrocytic parasite Babesia rodhaini (B. rodhaini). The present study focuseson the effect of AS101 administration on the acute phase of babesial infection where T helper cellsubset patterns—T H1 /T H2 —were assessed in heavily infected mice. Secretion of cytokines of the T H1 subset (IL-2, IFN-γ, IL-12) and of the T H2 subset (IL-10, IL-4) as well as TGF-β was measured following the administration of AS101 2 weeks before parasiteinfection. Our results demonstrate that the parasites suppress IL-2 protein and IL-12 mRNA andthat AS101 upregulates their secretion: IL-2, 8 u/ml vs 34 u/ml, respectively; IFN-γ protein, 2370 pg/ml vs 4777 pg/ml, respectively. Conversely, babesial infection results in the upregulation of IL-10 and IL-4 proteins and TGF-β transcripts, whereas AS101 downregulates their production: IL-10, 1800 pg/mlvs 360 pg/ml, respectively; IL-4, 58.3 pg/ml vs 24.5 pg/ml, respectively. A possible escape mechanisminduced by B. rodhaini is suggested, starting with IL-10 inhibition of macrophage activities leadingto a suppression of the T H1 response and of IL-2in particular. It is therefore possible that AS101may protect infected mice by activating cellular-mediated immunity and concurrently balancing the T H subset responses. It is suggested that AS101 may be effective as an antiparasitic drug.