Figure 3. Qdm and Qdm-like peptides stabilize pQa-1 at the cell surface.

(A) Following incubation of MEF-pQa-1cells with 100 μM Qdm (AMAPRTLLL) or OVA_257-264 (SIINFEKL) peptide at 37°C for 4 hr, surface pQa-1 and H2-K^b were analyzed by flow cytometry for comparison. (B) MEF-pQa-1were incubated with the indicated peptide (100 μM) at 27°C for 4 hr before staining for surface pQa-1. (C) Surface pQa-1 was FACS analyzed after incubation with 100 U/ml IFNγ for 24 hr. (D) Surface pQa-1 in a stably transduced TAP1-deficient (Tap1^-/-) fibroblast line was detected by FACS after incubation with or without 100 U/ml IFNγ for 40 hr. Representative of two analyses with mean ±SD of duplicates is shown. Bars in the figures represent mean ±SEM of two (C) or three (A and B) independent analyses using unpaired t test or one-way ANOVA, Dunnett's multiple comparisons test to compare with no peptide controls (*=p < 0.05; **=p < 0.01; ***=p < 0.001; ****=p < 0.0001; ns = not significant). Endogenous MHC-I K^b in these cells served as positive control.