PC7A initiates myeloid cell/CXCL9-CD8+ T/IFNγ feedback loop for T cell recruitment. (A) CXCL9 expression in different cell subpopulations from TC-1 tumors were measured by intracellular staining 24 hours after I.T. vaccination. (B) IFNγ expression in different cell subpopulations from TC-1 tumors were measured by intracellular staining 6 days after I.T. vaccination.(C) Quantification of CXCL9 and IFNγ mRNA expression in TC-1 tumor derived CD45+ cells 24 hours after PC7A, antigen peptide or vaccine I.T. treatment (n=3). (D) Quantification of CXCL9 mRNA in BMDM stimulated with PC7A-antigen or PC7A alone, antigen alone for 24 hours. (E) Intracellular staining of CXCL9+ cells in peritoneal macrophage stimulated with PC7A alone, antigen alone, PC7A-Antigen and IFNγ for 12 hours. (F) Chemotaxis assay of splenocytes derived from tumor bearing mice toward media with or without 900 ng/mL CXCL9. Migrated CD4 + T cells, CD8 + T cells, NK were quantified by flow cytometry. (G) BMDMs in the lower chamber were treatment with 100 µg/mL PC7A or 1 ng/mL IFNγ for 8 hours, chemotaxis assay of splenocytes derived from tumor bearing mice was quantified by flow cytometry. (H) Schematic of myeloid cell/CXCL9-CD8+ T/IFNγ and the effect of PC7A. In panels A–E, I.T. PBS was included as negative control. ****P<0.0001, ***p<0.001, **p<0.01, *p<0.05. One-way ANOVA t-test. ANOVA, analysis of variance; I.T., BMDM, bone marrow-derived macrophage; I.T., intratumoral; NS, not significant.