Figure 3.

Impaired HLA class I expression on a tapasin-deficient human lung cancer line. (A) Comparison between the tapasin-gene exon 2 sequencing traces of wild-type LHK2 and its variant YS3. The dash line starts with deletion/insertion mutation introduced by the CRISPR/Cas9-mediated genome editing system, followed by frameshift mutation occurred in both alleles. A solid line indicates the corresponding sequence of wild type showing homozygous alleles without mutation. (B) Western blot of LHK2 and YS3 treated with or without IFNγ, stained with tapasin- or actin-mAbs. (C) Flow cytometry of LHK2 and YS3 stained with an HLA-A24-specific c7709A2 mAb (pink), a W6/32 mAb (green), or without a primary antibody (black). (D) Quantification of surface HLA class I levels. ΔMFI values on the y-axis were calculated from three independent experiments shown in Fig. 3C, by subtracting values of negative controls without a primary antibody. Data are shown as mean + SEM (n = 3). p-values were calculated using a two-tailed t-test (**p < 0.01). The mean-percentage changes of YS3 compared with LHK2 in ΔMFI of HLA-A, B, C, and HLA-A24 are also shown.