Background:Metabolite intermediates of the branched-chain amino acid leucine such as β-hydroxy-β-methylbutyrate (HMB) modify and may improve both innate and specific immune function. Although HMB may act as a dietary immunomodulator, information about the effects of HMB on immune-related molecules (eg, cytokines) is lacking. In humans, HMB has been used to prevent body weight loss and skeletal muscle damage and to increase skeletal muscle mass and strength. Therefore, it is relevant to understand its immunomodulatory effects. Accordingly, this study examined the effects of HMB on specific protein expression and/or activation on lymphocytes and cytokine production.

Hypothesis:HMB exhibits dose-dependent modulation of lymphocyte proliferation and T-cell–derived cytokine production in vitro.

Subjects:8 healthy volunteers, age 23 to 45 years, who donated blood samples

Experimental design: In vitro, translational study

Treatments and protocol:Peripheral blood mononuclear cells (PBMCs) were isolated from venous blood collected and cultured under standard conditions. Cells were cultured in the presence of 0, 0.1, 0.5, 1, 5, and 10 mM HMB. Assessments included cell proliferation, cell-cycle analysis, and cytokine quantitation by bead array.