Fig 1: MHCII surface localization and secretion of the Treg chemokine CCL22 are altered by loss of Arp2/3 complex. (A) Left, Representative fluorescence histograms showing MHCII surface levels (APC-A) in WT control vs. WT stimulated (LPS/I), KO control vs. KO stimulated (LPS/I) and WT stimulated versus KO stimulated (LPS/I), obtained by reading 10,000 events via FACS measurement. Plots have been normalized to the mode of the data. Right, Average median intensity of APC-A fluorescence (staining MHCII) from WT and Arpc2-/- macrophages left untreated or stimulated for 24 h with LPS/IFN?, n= 3 independent experiments. ** p-value = 0.0089. (B) Left, representative images of surface MHCII staining from WT and Arpc2-/- macrophages at 24 h LPS/ IFN? stimulation. Scale bar = 30 µm. Right, average cellular MHCII surface staining. Error bars represent standard error of the mean. N = 3 independent experiments with at least 29 cells analyzed per condition in each experiment. (C) Average CCL22 chemokine secretion by WT and Arpc2-/- macrophages at baseline or after 24 h of LPS/IFN? stimulation, as measured by ELISA. N = 4 independent experiments, with p-values obtained via unpaired t-test. Error bars represent standard error of the mean. * p-value = 0.05. (D) Left, Mouse chemokine array blot of WT and Arpc2-/- culture medium after 24 h LPS/IFN? stimulation. Right, quantification of blot intensity for the 10 chemokines detected in these samples. Numbering on the graph corresponds to numbers on the raw blot data above. Each chemokine is spotted onto the membrane in duplicate. N = 2 independent experiments. Error bars represent standard error of the mean. * p-value = 0.05. (E) Average IL6 and TNFa secretion by WT and Arpc2-/- macrophages at baseline or after 24 h of LPS/IFN? stimulation, as measured by ELISA. Means are color coded by experiment. Error bars represent standard error of the mean. N = 4 independent experiments.