Fig. 4: HMGB1 is required for exosome-mediated PD1 ⁺ TAM expansion.

a, b HMGB1 protein expression was measured through western blot analysis (a) and qPCR (b) in paired ESCC tissues and non-tumor tissues (N, non-tumor tissues; T, tumor). c Serum HMGB1 levels were measured using ELISA in a healthy person and in patients with ESCC. d, e On day 3, monocytes cultured in the medium with or without exosomes or HMGB1 in the presence or absence of aHMGB1 were subjected to flow cytometric analysis to gauge the expression of PD1 in monocytes. Cross-sectional graphs are displayed in d. e Data stand for the average of three independent experiments. f, g Estimation of the inhibitory capability in monocytes cultured in the medium with or without exosomes or HMGB1 with or without aHMGB1 by flow cytometry. Representative graphs are shown in f. g Data mean the average of the three experiments conducted independently. h On day 3, monocytes cultured in presence or absence of exosomes or HMGB1 with or without aHMGB1 were evaluated the levels of CD64, HLA-DR, and CD206 in monocytes by utilizing flow cytometry. Data stand for the average of three independent experiments. i, j Estimation of IL-10 (i) and IL12p70 (j) level in monocytes cultured in the medium with or without exosomes or HMGB1 by ELISA. Data mean the average of the three experiments carried out independently. *p < 0.05, **p < 0.01, ***p < 0.001 (Student’s t-test)