Langerhans dendritic cells, tobacco smoke and lung tumours

The distribution of Langerhans dendritic cells in tobacco smoke related human lung cancer, tobacco smoke induced Langerhans cells changes during cutaneous and pulmonary carcinogenesis in mice were investigated. While dendritic cells were rare in normal lung, their density was marked in bronchioalveolar, well and moderately differentiated squamous cell carcinomas. Small cell lung cancer and poorly differentiated squamous cell carcinoma showed the lowest density. High density of dendritic cells in lung tumours was associated with marked tumour infiltrating lymphocytes and favourable survival. Exposure of mice to tobacco smoke increased the density of zinc-iodide-osmium positive pulmonary Langerhans cells. Pulmonary Langerhans cell granulomatosis and a proliferative alveolar and bronchial epithelial tumour-like lesions were observed. The density of pulmonary Langerhans cells returned to that of the control level after ceasing exposure to tobacco smoke and the interstitial granulomatous lesions disappeared, but the bronchial epithelial metaplasia did not reverse. The ultrastructure of the zinc-iodide-osmium positive cells was similar to that of pulmonary Langerhans cells. Tobacco smoke condensate increased the density, changed the morphology and impaired the function of epidermal Langerhans cells. This was associated with skin tumour development. While examining human lung lesions S100 positive DC were observed migrating into tumours. So these cells and their relation to LDC were further examined in blood. Metrizamide enriched dendritic cells isolated from human blood, were S100 positive, co-expressed CD45 and were non-phagocytic. Their diameter was larger than that of CD3 positive T lymphocytes and smaller than CD14 positive monocytes. The ultrastructural features were consistent with that of blood dendritic cells. Their number slightly decreased with age, equal numbers were observed in both sexes and formed 0.09 ± 0.07 cells x 10 9 per litre of blood.