Extended Data Fig. 9: LILRB4 promotes human M-MDSC suppressive function.

a, T cell proliferation assay of CFSE-labeled CD3⁺ T cells co-cultured with CD14⁺ MDSCs isolated from cancer patient peripheral blood. Cells were cultured in plates coated with BSA or SCG2 in the presence of anti-CD3/CD28 activation beads. Anti-LILRB4 blocking antibodies were added as indicated. T cell proliferation was assessed by flow cytometry (n = 3 biological replicates). b, Quantification and statistical analysis of Western blot results shown in Fig. 7c (n = 3 biological replicates). c, Immunoblot of CD14⁺ cells from cancer patient blood stimulated with or without IL-6 for 10 min in 96-well plates coated with BSA or SCG2. Lysates were analyzed using the indicated antibodies. d-e, Immunoblot (d) and quantification (e) of IL-6-STAT3 signaling activity in CD14⁺ cells from health blood stimulated with or without IL-6 for 5, 10 min in plates coated with BSA or SCG2 (n = 3 biological replicates). f, Percentage of human CD45⁺ cells in peripheral blood of humanized mice 8 weeks after CD34⁺ cells injection into NSG mice. Human cell engraftment was evaluated by flow cytometry. g, Immunoblot analysis confirming SCG2 ectopic expression in A375 melanoma cells transduced with pLVX-SCG2 lentivirus. h, Representative tumor images of the A375 tumor model in humanized mice intraperitoneally injected with anti-LILRB4 antibody or control IgG (n = 9 or 10). Data are presented as mean ± s.d. p values were determined by one-way ANOVA with Holm-Sidak’s multiple comparisons test (a), one-way ANOVA with Tukey’s multiple comparisons test (b), or two-way ANOVA with Bonferroni’s multiple comparisons test (e).

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