3.1 β-damascone was identified as an immunomodulator suppressing
DC-mediated T cell activation
To find novel immunomodulators, we performed 2-step screening using an
aroma-compound library (Supplementary Table SII ). By the 1st
screening, in which APC-dependent T cell proliferation was assayed, 22
candidates were selected from 150 compounds as immunosuppressors, and 3
compounds were passed through the 2nd screening evaluating the
suppressive effect on IL-2 release from OVA-pulsed OT-II splenocytes
(Supplementary Figure S1 ). Considering several factors, such as
IC50, we finally selected #177 β-damascone
(Figure 1A ), a major component of rose aromas. In accordance
with preliminary observations in the abovementioned screening,
β-damascone suppressed OVA-induced IL-2 production from OT-II
splenocytes (Figure 1B ) and APC-dependent proliferation of
CD4+ T cells (Figure 1D ) in a dose-dependent
manner at concentrations much lower than those showing cytotoxicity
(Figure 1C ). Although APC-independent T cell proliferation
caused by stimulation with plate-coated anti-CD3 and anti-CD28 Abs was
moderately suppressed by β-damascone (Figure 1E ), considering
that the development of Th1 cells induced by OVA-pulsed DCs
(Figure 1F ) but not by CD3/CD28 stimulation (Figure
1G ) was significantly suppressed by β-damascone, we focused on the
effect of β-damascone on the function of DCs.