Effect of IL-28A on HLA class I antigen expression in Huh7 cells. The Huh7 cells were treated with 2 ml IL-28A-conditioned culture medium for 72 hours. The cells were then harvested and incubated with HLA class I antigen-specific antibody labeled by FITC fluorescence, followed by flow cytometric analysis. The arrow-marked curve indicates control cells. The arrowhead-marked curve indicates cells treated with IL-28A.