PBMC and fibroblast cocultures to mimic the in vivo effect of BCG on trained immunity.

Abstract

BCG greatly stimulates innate immune cells. Previous studies demonstrated that BCG-stimulated monocytes develop trained immunity whereby they respond to homologous and heterologous antigens. Previous studies used isolated monocytes or animal models to study BCG-induced trained immunity, which have benefits and limitations. To approximate in vivo conditions, we stimulated peripheral blood mononuclear cells (PBMCs) with BCG-treated human fibroblasts. We found that compared with BCG stimulation, the addition of fibroblasts increased the expression of IFN-γ in NK and γδ T cells and of TNF-α and IL-10 in monocytes. We conclude that BCG-treated fibroblasts offer advantages over BCG alone for studying trained immunity.