Histochemical study on the pathogenesis of chlorocyclizine-induced pulmonary lipidosis.

Male rats were fed a diet containing chlorocyclizine in high concentrations for about 3 weeks. They lost weight and showed respiratory distress. The lungs contained clusters of foam cells in the alveoli. Acid esterase staining revealed reduction of activity in alveolar cells presumed to be granular pneumocytes and absence of activity in the foam cells. The lipid showed in the foam cells could not be stained with Sudan dyes, except at high temperature, and was not stained by phospholipid and cholesterol procedures. This indicated that the stored lipids are probably solid at room temperature, consisting of saturated triglycerides and/or phospholipids. It is suggested that the lipid originated in the granular pneumocytes. The drug might have deranged the esterase-phospholipase activity in these cells and in the macrophages.