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This study aims to investigate whether Guiqi Yiyuan Ointment can increase the sensitivity of Lewis lung cancer mice to cisplatin by reducing M2 macrophage polarization and decipher the possible mechanism. Ten SD rats were allocated into a Guiqi Yiyuan Ointment(1.2 g·kg~(-1)·d~(-1)) group and a blank group(an equal volume of normal saline). After continuous gavage for 7 days, the drug-containing serum was prepared. The cell counting kit-8(CCK-8) method was used to screen the optimal intervention concentration of 10% blank serum and 10% drug-containing serum. The cells were allocated into M0, M2(20 ng·mL~(-1) IL-4), M2+blank serum(20 ng·mL~(-1 )IL-4+blank serum), and M2+drug-containing serum(20 ng·mL~(-1) IL-4+drug-containing serum) groups and cultured for 48 h. The proportion of CD206~+ cells in each group was detected by flow cytometry. q-PCR was used to determine the mRNA levels of Janus kinase 3(JAK3), signal transducer and activator of transcription 6(STAT6), and arginase-1(Arg-1) in each group. Enzyme-linked immunosorbent assay(ELISA) was employed to assess the secretion levels of vascular endothelial growth factor(VEGF) and interleukin-10(IL-10) in each group. The cells were then cultured in fresh culture medium for 48 h, and the supernatant after centrifugation was collected as the conditioned medium. Lewis cells were treated with different groups of conditioned media and different concentrations of cisplatin(0-160 μmol·L~(-1)) for 24 h and the cell viability was examined by the CCK-8 method. Fifty SP-grade male C57BL/6 mice were modeled for Lewis lung cancer and then grouped as follows: model, cisplatin [0.005 g·kg~(-1)·(2 d)~(-1)], and cisplatin+low-, medium-, and high-dose Guiqi Yiyuan Ointment [0.005 g·kg~(-1)·(2 d)~(-1) cisplatin+1.6, 3.3, 6.6 g·kg~(-1)·d~(-1) Guiqi Yiyuan Ointment]. After continuous administration for 14 days, the mice were euthanized, and the tumor-bearing tissue was collected. The pathological changes of the tumor-bearing tissue were observed by hematoxylin-eosin staining. Immunofluorescence was used to detect CD206/CD68 ratio changes in the tumor-bearing tissue. Western blot was employed to measure the phosphorylation levels of JAK3 and STAT6 in the tumor-bearing tissue, as well as the expression of B-cell lymphoma-2(Bcl-2) and Bcl-2-associated X protein(Bax). ELISA was employed to measure the VEGF and IL-10 levels in the tumor-bearing tissue. The results of cell experiments showed that compared with the M2 group, the M2+drug-containing serum group showed decreased CD206~+ cells, down-regulated mRNA levels of JAK3, STAT6, and Arg-1, declined VEGF and IL-10 secretion levels, and weakened cell viability. In the animal experiments, compared with the model group and cisplatin group, the combined group showed increased apoptosis and necrotic areas, decreased CD206/CD68 ratio, down-regulated JAK3 and STAT6 phosphorylation levels and Bcl-2 expression level, up-regulated Bax expression level, and lowered VEGF and IL-10 secretion levels. In conclusion, Guiqi Yiyuan Ointment may increase the sensitivity of Lewis lung cancer mice to cisplatin by inhibiting the JAK3/STAT6 pathway and reducing the polarization of M2 macrophages.