IL-15 inhibits the migration of immature B cells in an IFN-γ–dependent manner. (A-C) Total B cells from control (mature; A) Ii^−/− (immature; B) or IFN-γ^−/− (C) mice were suspended in 1 mL RPMI plus 10% FCS and incubated for 1 hour in the presence or absence of IL-15 (30 ng/mL); their actin polymerization was analyzed as described in “Cytoskeleton rearrangement.” The results are representative of 3 separate experiments. Error bars represent SD.