Extended Data Fig. 8: Cromolyn mobilizes antigen-presenting machinery of mast cells.

(a) Comparison of activity scores for indicated gene signatures between apMCs and other functional states in human TNBC. A total of 1,064 mast cells were included. (b, c) In vitro assay to identify clinically available medications that could facilitate antigen-presenting machinery of mast cells. Human (b, n = 5) and mouse (c, n = 3) mast cells were cultured in individual medium with or without indicated medications for 5 days. Flow cytometric analyses for the percentage of MHC-II⁺, CD40⁺, CD80⁺, and CD86⁺ cells are shown (compared with vehicle). ns, P ≥ 0.05; *P < 0.05; **P < 0.01; ***P < 0.001. (d) OT-II CD4⁺ cell activation after stimulation with cromolyn or vehicle-pretreated mast cells via direct or indirect coculture system (n = 6). (e) OT-II CD4⁺ cell activation after stimulation with cromolyn or vehicle-pretreated mast cells (n = 6). (f) OT-II CD4⁺ cell activation after stimulation with cromolyn or vehicle-pretreated mast cells isolated from Cpa3^CreERT2Cd74^fl/fl conditional knockout or Cd74^fl/fl control mice (n = 6). (g) Hepatic and renal function levels measured from 4T1 tumor-bearing mice at the endpoint in Fig. 3n (n = 6). ALT, alanine aminotransferase; AST, aspartate aminotransferase. (h) Flow cytometry and Immunohistochemistry staining analyses in 4T1 tumors from each treatment group in Fig. 3n (n = 6). (i) Flow cytometry and Immunohistochemistry staining analyses in AT3 tumors from each treatment group in Fig. 3o (n = 6). (j) AT3 tumor cells were orthotopically injected into wild-type and B6.Cg-Kit^W-sh mice, which then received cromolyn or vehicle (n = 6). Growth curves and tumor weights at the endpoint in each group were shown. (k) Growth curves and tumor weights at the endpoint in mice treated with cromolyn or in combination with ACK2 neutralization or IgG isotype control in 4T1 orthotopic tumors (n = 6). (l) Functional markers of CD8⁺ T cells measured using flow cytometry from tumors in Fig. 3p (n = 5). Relative MFI of markers expressed on CD8⁺ T cells in each group compared with that in the Cd74^fl/fl + control group was shown. MFI, mean fluorescence intensity. Data are mean ± s.e.m. Two-sided Mann-Whitney test (a), unpaired Student’s t-test (b–i, j, k for tumor weight, l), two-way ANOVA (j, k for tumor volume).

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