Hydrolysable tannins, gallic acid, and ellagic acid in walnut reduced 3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium bromide (MTT) reduction in T-Cells cultured from the spleen of mice

Abstract

Walnut is an allergenic food in some populations. Although some allergenic proteins have been identified in walnuts, few small molecule components in the food have been evaluated for their immunomodulatory functions. To examine the immunomodulatory functions, we cultured T-cells from the spleen of mice with small molecule compounds in walnut, measured 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) reduction in the cells and assessed the T-cell activation and growth. Of the nine compounds of walnut, three compounds decreased the T-cell activation and growth in anti-CD3/CD28 antibody-stimulated spleen cells of mice, whereas five compounds increased that. Because the three compounds, pedunculagin, casuarictin, and pentagalloylglucose that decreased the T-cell activation and growth belong to the hydrolysable tannin class, we inferred that the tannins would be hydrolyzed in a culture containing fetal bovine serum to yield gallic acid and/or ellagic acid. Therefore, we assessed the effect of these two compounds on the T-cell activation and growth and cytokine secretion in the culture. Both compounds decreased the T-cell activation/growth and the secretion of interleukin-4, interleukin-10, and interferon-γ. These results suggested that walnuts contained compounds that either suppressed or promoted T-cell growth and that supplementation of hydrolysable tannins to walnut-containing foods might ameliorate allergic reaction by walnut consumption.