A natural oil increases specific anti-OVA IgG levels and induces a cellular immune response combined with aluminum hydroxide

The efficacy of certain vaccines is improved by the use of adjuvants. Nowadays, the development of new, effective, and safe adjuvants that stimulate the innate immune response is researched. In this context, medicinal plants appear as a suitable alternative.Minthostachys verticillataessential oil (EO) has demonstrated the ability to modulate mechanisms of the innate immune response. Thus, the present work aimed to evaluate the EO adjuvant effect on humoral and cellular immunity, coadministered with OVA as antigen. The chemical analysis of EO by gas chromatography-mass spectrometry revealed a predominant pulegone-menthone chemotype. EO (1.25, 2.5, or 5.0 mg/ml) did not alter the viability of murine fibroblasts (3T3 cell line) neither showed signs of toxicity in Balb/c mice inoculated subcutaneously. The serum of mice immunized with OVA + EO showed increased levels of anti-OVA-specific antibodies of IgG1 subclass compared with the mice immunized with OVA alone revealing an adjuvant effect of EO. The delayed type hypersensitivity showed that the combination OVA + Al(OH)(3) + EO was the best to induce a cellular immune response that extended until 48 h postinjection of OVA.M. verticillataEO appears as a new, safe, and effective adjuvant, which should continue to be studied for their possible future incorporation into vaccine formulations.

Automated summary

The study demonstrates that essential oil from Minthostachys verticillata acts as a new, safe, and effective adjuvant by enhancing antibody levels and inducing cellular immune responses, potentially improving vaccine efficacy.