IL-10-mediated signals act as a switch for lymphoproliferation in Human T-cell leukemia virus type-1 infection by activating the STAT3 and IRF4 pathways
Fig 5
Critical roles of IRF4 in expansion of ILTs.
A. Intracellular IRF4 expression (solid line) was analyzed in various ILT cells following incubation with or without IL-10 for 7–11 days. Closed histograms represent staining with control antibody. The numbers indicate the proportions (%) of cells with high IRF4 expression. B. ILT-294 (cultured with rhIL-10), ILT-22, and ILT-H2 cells were transfected with si-CTRL and si-IRF4, and the cell lysates were subjected to immunoblot assays for cleaved caspase-3, caspase-3, survivin, and β-actin 48 hours after electroporation. Approximate sizes of caspases are indicated. a, b, c, denote the same images for β-actin because the same membranes were used, respectively. C. Indicated ILTs and Jurkat cells were transfected with si-CTRL, si-STAT3, or si-IRF4, and the total viable cell count were evaluated 3 days after electroporation by trypan blue exclusion test. The data represent the mean and SD of duplicate or triplicate samples. The immunoblot confirming the knockdown efficiency of STAT3 in Jurkat cells is also indicated. IRF4 was not detectable in Jurkat. D. Intracellular IRF4 and Ki67 expression of the ILTs prepared in C were analyzed by flow cytometry. ILT-294 cells were cultured in the presence of IL-10 in B, C, D. Numbers in D indicate the proportion (%) of cells in each quadrant. Similar results were obtained in two independent experiments. * p<0.05, ** p<0.01.