Extended Data Fig. 5: Functional inhibition of CD8 T cells by exosomal PD-L1.
From: Exosomal PD-L1 contributes to immunosuppression and is associated with anti-PD-1 response
a, The log2-transformed RPPA data showing the levels of PD-L1 in the exosomes secreted by control (MEL624) or PD-L1-expressing (PD-L1/MEL624) human melanoma MEL624 cells (Bottom). b, Immunoblots for PD-L1 in the whole cell lysate (W) or in the purified exosomes (E) from MEL624 or PD-L1/MEL624 cells. The same amount of protein was loaded in each lane. The experiments were repeated two times independently with similar results. For source data, see Supplementary Fig. 1. c, PD-L1 on the surface of exosomes secreted by MEL624 or PD-L1/MEL624 cells as determined by ELISA. d, Levels of PD-L1 on exosomes secreted by MEL624 or PD-L1/MEL624 cells, as measured by ELISA. e, qPCR analyses of IL-2, IFN-γ, and TNF in human peripheral CD8 T cells (stimulated with anti-CD3/CD28 antibodies) after treatment with MEL624 cell-derived exosomes, PD-L1/MEL624 cell-derived exosomes or WM9-cell-derived exosomes with or without blocking by IgG isotype or the anti-PD-L1 antibodies. The relative mRNA expression level was calculated as the ratio to the control cells. f, ELISA of IL-2, IFN-γ, and TNF in human peripheral CD8 T cells (stimulated with anti-CD3/CD28 antibodies) after treatment with MEL624 cell-derived exosomes, PD-L1/MEL624 cell-derived exosomes or WM9-cell-derived exosomes with or without blocking by IgG isotype or PD-L1 antibodies. g, Representative histogram of CFSE-labelled human peripheral CD8 T cells (stimulated with anti-CD3/CD28 antibodies) after treatment with WM9 cell-derived exosomes with or without antibody blocking (left). The proportion of cells with diluted CFSE dye is shown (right). h, Representative contour plots of human peripheral CD8 T cells (stimulated with anti-CD3/CD28 antibodies) examined for the expression of granzyme B (GzmB) after treatment with WM9 cell-derived exosomes with or without antibody blocking (left). The percentage of GzmB+ CD8 T cells stimulated with anti-CD3/CD28 antibodies is shown at the right panel. Data represent mean ± s.d. of three (a, c, e, f, h) or four (d, g) independent biological replicates. Statistical analyses are performed using two-sided unpaired t-test (d–h).
