Fig. 4

Compared with FDCs, macrophages and neutrophils are capable of presenting antigens to lung B cells but have much shorter kinetics in the lymph nodes. A Comparison of the frequencies of different APC populations in the lung and lymph nodes (see Supplementary Fig. S5 for gating). The symbols represent data from six mice from one representative experiment, and the bars represent the means. Three experiments with a total of 14 animals were performed. B Flow cytometry analysis of antigens retained on different APC populations in the lymph node and lung. The mice received fluorescent antigen four days (blue open histograms) or 24 h (purple filled histograms) prior to analysis. The gray lines show the autofluorescence background of the different cell types in the mice not challenged with the fluorescent antigen. Histograms are concatenated data from three animals. The data are representative of four experiments (12 mice), where the antigen was given 24 h prior to analysis. In only two of these four experiments, the additional group (6 mice), which received antigen 4 days prior to analysis, was included. C Immunohistological analysis of antigen-specific B cells and fluorescent antigen (see above) together with FDCs (CD21/35), macrophages (F4/80), or neutrophils (Ly-6G). The arrows at high magnification indicate B cells interacting with antigen-loaded macrophages or neutrophils. Data representative of two independent experiments with a total of 10 mice are shown. D Same analysis as in panel c; however, the last antigen application was four days before analysis. Representative tissue sections from two animals. The scale bars in all figures indicate 50 µm