Figure 3.

Silicotic rat lung macrophages, particulate-stimulated normal rat lung macrophages, and particulate-stimulated J774 cells induce lung fibroblast collagenase-3 gene expression. (A) Rat lung macrophages were isolated by BAL from silicotic rat lungs 7 d after intratracheal instillation of silica and allowed to condition medium for 24 h. Similarly, macrophages were isolated by BAL from normal, healthy rat lungs and allowed to condition medium for 24 h when unstimulated or in the presence of silica (0.1 mg/ml) or zymosan (4 mg/ml). Primary cultures of ALFs were untreated (lane 1), treated with 50% silicotic rat lung macrophage-conditioned medium (CM) (lane 2), treated with 50% unstimulated normal macrophage-CM (lane 3), treated with 50% silica-stimulated normal macrophage-CM (lane 4), or treated with 50% zymosan-stimulated normal macrophage-CM (lane 5); cultures were harvested after 48 h for Northern blot analysis of collagenase-3 (C’ase) and glyceraldehyde-3-phosphate dehydrogenase (GAP) mRNAs. (B) Murine monocytic J774 cells were allowed to condition medium for 24 h when unstimulated or in the presence of silica (0.1 mg/ml) or zymosan (4 mg/ml). Primary cultures of ALFs untreated (lane 1) or treated with 50% unstimulated J774-CM (lane 2), silica-treated J774-CM (lane 3), or zymosan-treated J774-CM (lane 4) were harvested after 48 h for Northern blot analysis as above.