3.2. Immunomodulatory effects of MQL on splenocytes from BALB/c mice immunized by OVA
BALB/c mice were immunized twice with OVA and alum, then splenocytes were isolated. Using this ex vivo system, we investigated whether MQL treatment regulates allergic immune responses by suppressing cell proliferation via increased HO-1 expression.
OVA-induced Th1- (IFN-γ) and Th2-related cytokines (IL-4, IL-5, and IL-13) were significantly suppressed by MQL treatment (Fig. 2A-D) . Next, to investigate whether the immunomodulatory effects of MQL were a consequence of decreased cell proliferation, we measured proliferation and IL-2 production. Notably, MQL treatment suppressed IL-2 production as well as splenocyte proliferation (Fig. 2F and G) . To further characterize these T cell subsets, we analyzed Th1- (STAT1) and Th2-associated transcriptional factor (STAT6), as well as HO-1. Figures 2H and I show that STAT6 and STAT1 phosphorylation were reduced by MQL treatment, whereas HO-1 expression was increased by MQL. Interestingly, however, the Th1-related cytokine IL-12 was increased by MQL treatment (Fig. 2E) . These results indicate that MQL treatment largely inhibits Th1- and Th2-related immune responses via reduction of cell proliferation induced by HO-1 up-regulation.