Fig. 1

Particle instillation causes pulmonary neutrophil accumulation. (i) Monocytes and neutrophils in bronchoalveolar lavage fluid (BALF) were identified by nuclear morphology in haematoxylin and eosin-stained cytospins after in vivo administration of diesel exhaust (DEP; 2, 6 or 24 h) or control (carbon black (CB); DQ12 quartz; 6 h) particle solutions. DEP and CB were associated with inflammatory cells (arrows) or phagocytosed by macrophages (arrow heads). There was no evidence of phagocytosis of quartz particles. Magnification ×400. (ii) Instillation of DEP (0.5 mg/rat; black columns) caused a transient increase in total cell number that peaked 6 h following administration. CB (0.5 mg/rat; light grey columns) or DQ12 quartz (0.125 mg/rat; dark grey columns) also increased cell number 6 h after instillation. (iii) Increases in total inflammatory cell number were due to an increase in neutrophils. Data are mean ± s.e.mean (n = 6) and were compared with appropriate control using Student’s unpaired t-test. *P < 0.05, ***P < 0.001