Fig 1: EBV-infected B cells undergo diapedesis.a Spontaneous diapedesis of primary resting B cells, B cells stimulated with CD40L and IL-4 or CD40L, IL-4 and CXCL12, and of EBV-infected B cells through a layer of human brain microvascular endothelial cells (HBMEC) cells. Bar graphs give the mean and standard deviation of cells that had migrated after 24 h of culture (n = 6 independent B cell samples). Created in BioRender. Poirey, R. (2025) https://BioRender.com/qnmhdf1. b We determined the ability of various B cell populations (see a)) to adhere to HBMEC cells under constant flow conditions, with or without prior stimulation with TNF-α. The graph shows the concentration of cells bound to the endothelial layer achieved by the different B cell populations. The effect of defactinib (Def.) (3.5 μM) or of an LFA-1 inhibitor (BIRT377 50 μM) on EBV-infected B cell adhesion is also described. Bar graphs give the mean and standard deviation (n = 5 independent B cell samples). c HBMEC and HUVEC endothelial cells were cocultured with EBV-infected B cells for 30 min. The effect of coculture on ZO-1 expression was evaluated 24 h later by immunofluorescence. Its localization was determined by intensity profiling of gray values, membrane peaks being marked with arrows (middle panel). Bar graphs give the percentage and the standard deviation of cells that have a membrane peak (n = 5 independent B cell samples). d Same as in (c), but cells were analyzed for ICAM-1 expression. The bar graphs give the raw integrated density of fluorescence (Raw/Int/Den) in the different samples (n = 5 independent B cell samples, graphs showing mean and standard deviation). e Primary B cells labeled with a green fluorescent dye were mixed or not with EBV-infected B cells and placed above an endothelial cell layer. The relative number of primary B cells that crossed the endothelial barrier under both conditions after 24 h is given in the bar graph as mean with standard deviation (n = 6 independent B cell samples). f Same experiment as described in (e), but the stay and move populations were stained for CD11c. The relative proportion of CD11c+ cells in these two subsets was determined (n = 5 independent B cell samples, 1000 cells recorded). The graph shows the mean of these proportions with their standard deviation in cell populations that underwent coculture with EBV-infected B cells. The results are given relative to the CD11c+ proportions in the absence of coculture. Statistical significance was determined using one-way analysis of variance in (a) and (b) and two-sided paired t tests in (c), (e), and (f) and unpaired t test in (d). *p < 0.05, **p < 0.01, ***p < 0.001 and ****p < 0.0001. Source data are provided as a Source Data file.