Tubular pathology and apoptosis are markedly increased in IL-15^–/– kidneys during NSN. Tubular damage is increased in IL-15^–/– kidneys (a) compared with IL-15^+/+ kidneys (b) with NSN measured on day 11 after induction (inset; arrow indicates damaged tubule). Tubular damage (c), and apoptosis (d) (measured on day 11 by TUNEL assay) are increased during NSN in IL-15^–/– kidneys. Data were analyzed by Student t test and are presented as mean ± SEM. n = 8 per group. *P < 0.05. Magnification: a and b, ×100; insets, ×400.