It is accepted that inflammation plays a critical role in the development of atherosclerosis; the pathogenesis is not clear. B-cell-produced interleukin (IL) 10 is an immune regulatory cytokine that can inhibit immune inflammation. This study tests a hypothesis that a psychological stress hormone, cortisol, suppresses IL-10 expression in peripheral B cells of patients with atherosclerosis. Peripheral blood samples were collected from patients with coronary artery atherosclerosis. B cells were isolated from the blood samples to be analyzed for the expression of IL-10 and micro RNA (miR) 98 by real-time polymerase chain reaction. We observed that the frequency of IL-10(+) B cell was less in patients with atherosclerosis than healthy controls. The serum cortisol levels were higher in the patients than that in healthy controls. Peripheral B-cell frequency was negatively correlated with the serum cortisol levels. Exposure of B cells to cortisol increased the expression of miR-98 in B cells. Cortisol also inhibited the expression of IL-10 in B cells, in which miR-98 played a critical role. Treating B cells from atherosclerosis patients with anti-miR-98 liposomes reversed the ability of expression of IL-10 in the cells. The expression of IL-10 is suppressed in peripheral B cells, which can be up regulated by anti-miR-98 liposomes.