In vitro induction of anti-type 2 T cells by glycyrrhizin

Glycyrrhizin (GR), an active component of licorice roots, has been previously shown to induce the generation of anti-type 2 T cells (anti-BI2T cells), which are able to counteract the activity of burn-induced CD8+ type 2 T cells (BI2T cells), in thermally injured and normal mice. In the present study, anti-BI2T cells were generated in vitro in cultures of spleen cells stimulated with GR. Anti-BI2T cells were induced in vitro when splenic mononuclear cells (SMNC) were stimulated in vitro for 24 to 72 h with 0.1–10 μg/ml of GR. Anti-BI2T cell activity was detected when suppressor macrophages (Mφ) were depleted from SMNC after stimulation with GR. However, the GR-stimulated generation of anti-BI2T cells required the participation of Mφ or their sonicated fractions. Anti-BI2T cells induced in vitro by GR were identified as Vicia villosa lectin adherent IFNγ producing-CD4+ T cells lacking the ability to produce IL-2, IL-4 or IL-10. These results indicate that anti-BI2T cells are generated by GR in vitro. Mφ are not only necessary for the generation of anti-BI2T cells induced by GR but also inhibit their activity.