Fig. 2: MHC-I knockout promotes immune cell evasion and metastasis in SCLC mouse models.

a Schematic of B2M KO generation in murine SCLC primary cell line. Created in BioRender. Meder, L. (2025) https://BioRender.com/4u5k5v3. b, c Relative MHC-I or PD-L1 expression of WT and MHC-I KO cells analyzed by flow cytometry, determined by mean fluorescence intensity (MFI) normalized to IgG control. Histograms of one representative experiment are shown (n = 3 biological replicates). d Schematic of experimental setup showing intravenous injection of MHC-I KO and WT cells into immunocompetent C57BL/6/immunodeficient NSG mice, tissue harvest and subsequent IHC and FACS analyses. Created in BioRender. Meder, L. (2025) https://BioRender.com/w6kb2vb. e Representative images of H&E-stained livers and intestinal lymph node tissues from iv. WT and MHC-I KO injected immunocompetent mice. Scale bars, liver 2.5 mm, for lymph nodes 1 mm. Additional FACS based quantification of liver tumor cell infiltration (n = 4 mice per group). f Representative images of CD45 and CD3 IHC staining in liver tissue from WT and MHC-I KO-injected mice. Quantification was performed using QuPath analysis with 5 regions of interest (ROIs) analyzed per individual (n = 2 per group). g Representative histograms showing CD107a expression measured by flow cytometry and corresponding quantification (WT n = 4 mice, MHC-I KO n = 5 mice). h Representative images of H&E- and NCAM1-stained liver tissue of MHC-I KO and WT injected immunodeficient NSG mice (MHC-I KO n = 3, WT n = 4) and quantification of tumor cell infiltration in 5 representative ROIs by QuPath analysis. Scale bars, H&E 2.5 mm, NCAM1 100 μm. Statistical analysis was performed using a two-sided, unpaired Student’s t-test. Data in this figure are shown as mean ± SEM. ns not significant, *p  <  0.05, **p  <  0.01, ***p <  0.001. Source data are provided as a Source Data file.