Figure 1.

Interstitial cell changes over time following instillation with SiO₂. Following an initial loss in cell number, exposure to SiO₂ increased the number of interstitial leukocytes recovered from the lungs over time compared with saline control (A). Within the interstitial immune cells recovered at 14 days post- SiO₂ exposure, each of the four subpopulations of lymphocytes examined was augmented compared with saline control, although the ration amongst the cell populations remained unchanged (B). Values are means ± sem; n = 5 mice/group; *P < 0.05 compared with saline control. The percent (C) and absolute number (D) of NK1.1⁺ CD3^– NK cells increased at 3, 7, and 28 days but decreased at 16 weeks post-SiO₂ exposure compared with saline. No change was observed at Day 1 in the percent or the absolute number. Values are means ± sem; n = 8–13 mice/group; *P < 0.05 compared with saline control.