Blood from 3 healthy donors was used to separate peripheral blood mononuclear cells, using Ficoll-Paque separation media (GE Healthcare). MLR was essentially performed as previously described.38 (link) Further details are in the supplemental Material and methods. After 48 hours, all samples were treated for 5 hours with Golgi plug protein transport inhibitor, brefeldin (BD Biosciences) to inhibit cytokine accumulation in the Golgi complex and processed to measure interferon-γ (IFN-γ) production by CD4+ and CD8+ T cells by flow cytometry.