Selective lymphocyte homing in mice with a B- or a T-cell–specific IFNAR deletion. (A) CD19-Cre^+/–IFNAR^flox/flox and CD4-Cre^+/–IFNAR^flox/flox mice were given injections of poly(I:C) or PBS. On day 1, B and T cells from spleen and from axillary and inguinal lymph nodes were subjected to FACS analysis. B/T cell ratios are depicted and are expressed as mean ± SD for 25 CD19-Cre^+/–IFNAR^flox/flox and 13 CD4-Cre^+/–IFNAR^flox/flox mice (as in Figure 3B). *P = .012 (PBS vs poly(I:C)). (B) B cells from WT and IFNAR^–/– mice were labeled with TAMRA or CFSE and reinjected into WT recipients. Labeled cells were counted in blood before and after treatment with poly(I:C). Single-cell suspensions of spleen and LNs were analyzed by FACS. Percentages and ratios of WT/IFNAR^–/– B cells are depicted. Results are representative of 1 of 3 animals in 3 similar experiments (as in Figure 2B). (C) Splenic morphology 15 hours after poly(I:C) injection. Staining of metallophilic macrophages (MOMA-1, green) delineates the marginal zone. The arrow indicates the marginal zone devoid of B cells. Images were visualized and acquired using an Olympus BX51 fluorescence microscope (Olympus, Center Valley, PA) equipped with a 10×/0.3 NA air objective. FluorSave reagent (Calbiochem, San Diego, CA) was used as imaging medium.