Flow cytometry analysis of mb-IL-15 expression on human spleen myofibroblasts. (A) Flow cytometry analysis using a rabbit polyclonal IgG anti-IL-15 revealed a mb-IL-15 form on human spleen myofibroblasts 72 hours after seeding (basal). Treatment during the spreading period with neutralizing mAbs directed against: IL-15 (10 μg/mL mAb247 recognizing the γc chain epitope); the IL-15Rβ chain (10 μg/mL mAb Mikβ1) and the γc chain (10 μg/mL mAb TUGh4) inhibited the expression of mb-IL-15. Use of neutralizing mAb against the IL-15Rα (10 μg/mL mAb M165) had no effect. The thin gray line defines IgG control; the bold black line defines mb-IL-15 expression. Treatment of spread cells had no effect. These data are representative of 3 different experiments. (B) Modulation of cell spreading in NHS7 cells treaded with 10 μg/mL of the neutralizing anti-IL-15 mAb247 or with a nonrelevant isotype-matched mAb recognizing the IL-13Rα2 subunit. These data are representative of 2 different experiments. Pictures were obtained with an Olympus microscope and a 40 ×/1.0 objective lens (Olympus, ArcuEil, France) using a Cool-Pix 995 numeric camera (Nikon, Paris, France).