Evaluation of the adjuvanticity of artemisinin with soluble Leishmania major antigens in BALB/c mice

Objective

To determine the adjuvant potential of artemisinin with a soluble leishmanial antigen in vaccinating BALB/c mice.

Methods

Seventy two female BALB/c mice were randomly assigned into six groups. The mice were vaccinated with soluble leishmania antigens (SLA) alone, artemisinin co-administered with SLA, SLA and Bacille Calmette Guérin (BCG) vaccine, and artemisinin and BCG alone. Unvaccinated mice formed the control group. The induction of cell-mediated immunity following vaccination was determined by measuring in vitro lymphocyte proliferation and the production of interleukin (IL)-4, IL-5 and gamma interferon (IFN-γ) determined by flow cytometry. Protection against L. major was determined by quantifying parasite burdens in L. major infected footpads using a limiting dilution assay and by measuring lesion sizes of the infected footpad compared to the contralateral uninfected footpad.

Results

Mice receiving SLA plus artemisinin produced significantly high levels of IL-4 and IL-5 (P < 0.05) and low levels of IFN-γ, resulting in exacerbated disease. In addition, subcutaneous administration of SLA + artemisinin, artemisinin alone or SLA alone resulted in the development of large footpad swellings and high parasite loads that were comparable to those of the control unvaccinated mice (P > 0.05), resulting in exacerbated disease.

Conclusion

These data suggest that artemisinin is not a suitable adjuvant for Leishmania vaccines. However, since artemisinin has been shown to be effective against Leishmania parasites in vitro and in vivo, further studies ought to be conducted to determine its immunochemotherapeutic potential when co-administered with Leishmania antigens.