The Plant Compound Sulforaphane Attenuates Induction of Cytokines and Other Early Activation Events in Jurkat Cells

Sulforaphane (SFN), a bioactive isothiocyanate found in cruciferous vegetables, has gained considerable interest for its anti-inflammatory and immunomodulatory properties. Previous work in our lab demonstrated that tert-butylhydroquinone (tBHQ), a common food preservative and synthetic antioxidant, suppresses early T cell activation events, including production of interleukin-2 (IL-2) and other cytokines, cell proliferation and induction of interleukin-2 receptor alpha (CD25) and other inducible cell surface receptors. Based on these findings, the current study explores the effects of sulforaphane (SFN), a naturally-occurring antioxidant, on Jurkat T cell activation. Considering that sulforaphane exists as multiple isomers - the functional implications of which on T cells is unclear, we investigated the individual effects of SFN isomers on CD4⁺ Jurkat T cell activation. Jurkat T cells were treated with 1, 3, 5, 10, 15, and 20 µM of either L-SFN or DL-SFN, following activation with anti-CD3/anti-CD28 for 24 h. Cell stimulation was assessed by measuring induction of activation markers using flow cytometry, and IL-2 cytokine secretion by ELISA. SFN inhibited upregulation of CD25, CD69, CD86, OX40 ligand (CD134) and CD40L (CD154) in a concentration-dependent manner. Likewise, SFN decreased induction of IL-2 secretion. Notably, both SFN isomers exhibited comparable suppressive effects on T cell activation. Taken together, these findings indicate that SFN suppresses induction of IL-2 and cell surface receptors in response to T cell stimulation, with no notable differences between isomers. These findings underscore the immunomodulatory properties of the dietary supplement SFN and specifically demonstrate inhibitory effects on T cell activation.