Total number of neutrophils (A), macrophages (B), and total protein (C) in bronchoalveolar lavage fluid of Mt1/2(+/+) and Mt1/2(+/+) mice exposed to 150 ± 15 μg Ni2+/m3 for 24, 48, or 72 h, or nonexposed control animals (n = 4–6 mice/group). Data are presented as means ± SEM. *Significant difference from nonexposed control group, P < 0.05. +Significant difference from Mt1/2(+/+) group, P < 0.05.