Bleomycin toxicity is characterized by destruction of:

Ans. b. Type I pneumocytes Bleomycin toxicity is characterized by destruction of Type I pneumocytes.Histopathotogy of Lung in Bleomycin Toxicity* Endothelial cell edema and blebbing* Necrosis of type 1 pneumocytes* Proliferation of fibroblast and fibrosis* Hyperplasia and metaplasia of type II pneumocytes* Inflammatory infiltrate with PMNBleomycin* Bleomycin is well known to cause pulmonary toxicity.* Incidence of bleomycin induced pulmonary toxicity is 5% for a total cumulative dose of 450 units and 15% for higher dosages.* Bleomycin is concentrated preferentially in the lung and is inactivated by hydrolase enzyme. This enzyme is relatively deficient in lung tissue. This may explain relative sensitivity of bleomycin to lung tissue.Type I pneumocytes are more vulnerable to bleomycin toxicity' and are destroyed by bleomycinPathological Features of Bleomycin Toxicity* Early endothelial cell damage* Destruction uf type 1 pneumocytes* Migration of type II pneumocytes into alveolar spaces inducing interstitial changesFollowing destruction of type I pneumocytes repair is characterized by hyperplasia and dysplasia of type II pneumocytes. Fibro- blast proliferation with subsequent pulmonary fibrosis is probably the basis for irreversible changes induced by Bleomycin.