Figure 3: PD-L1 blocking increased in vitro IFN-γ, IL-10, and TNF production, predominantly by CD4+ T cells in response to A(H1N1)pdm09 virus. Cytokine levels in the supernatants (SN) of PBMCs cultured for 7 days as described in Figure 2 and PBMCs stimulated with hemagglutinin (HA) for 7 days were measured with a Th1/Th2/Th17 human cytometric bead array kit (CBA). The production of IFN-γ (a), IL-10 (b), and TNF (c) by PBMCs is shown. Isolated memory CD4+ T cells (Tm) and sorted cDCs were co-cultured with or without PD-L1 blocking for 7 days, and cytokine production in the SNs was measured; IFN-γ (d), IL-10 (e), and TNF (f) levels are shown. Results are duplicates from 3 independent experiments and error bars indicate SEM. pH1N1: A(H1N1)pdm09 virus; SEB: staphylococcal enterotoxin B. * by Student’s -test.