FIG 6.

Defective IAV RNAs elicit cell-intrinsic and paracrine upregulation of class I HLA proteins. (A) A549 cells were treated with conditioned medium containing UV-inactivated culture supernatant from FM-MA-infected cells. Surface HLA levels on recipient cells (17 h posttreatment) and infected donor cells (17 hpi) were determined by flow cytometry. Histograms from a representative experiment are shown. Vertical dashed-lines indicate the expression level in uninfected cells. (B) MFI of cell surface HLA proteins on recipient cells from A relative to cells treated with conditioned media from mock-infected cells. Each data point represents an independent experiment. (C) A549 cells were treated with conditioned medium from cells transfected with IAV minireplicon expressing defective vRNAs from genome segment 5 or from control untransfected cells or pUC19 vector-transfected cells. After 24 h, cells were fixed and immunostained with a pan-anti-HLA-A/B/C antibody (n = 3). Histograms from a representative experiment are shown on the left; vertical lines indicate the expression level of targets in uninfected cells. On the right, relative MFI values from at least 3 independent experiments are shown (*, P < 0.05).