EXPERIMENTAL DISEASE Eosinophil and Foam Cell Accumulation in Lungs of Sprague-Dawley Rats Fed Purified, Bio tin-Deficient Diets

One hundred twenty male Sprague-Dawley rats (3 weeks old) were given biotin-deficient diets containing ovalbumin as the protein source. Ten control rats of the same origin were fed a commercially available purified diet that used casein as a protein source. Eosinophils and histiocytes were observed at a higher frequency in lungs of rats fed the purified diets containing ovalbumin than in the controls. Foam cells were confined to subpleural and peribronchial regions, reacting positively to anti-lysozyme antibody. The incidence ofpulmonary histiocytosis was 76/ 120 rats (63.3%) in the groups fed the ovalbumin-containing diets as compared with 1/10 (10.0%) in the controls. The accumulation of eosinophils in lung was highest (6124 rats, 25%) at 3 months. This lesion was not seen in the controls. Eosinophils were first observed in the penvascular and peribronchiolar regions. In advanced lesions, macrophages and mast cells also appeared in the lesions, which at this stage resembled so-called idiopathic chronic eosinophilic pneumonia of human beings. Neither foam cells nor eosinophils were present in any of the other organs. Because there was no difference in the composition of the diets with the exception of the protein source, these lung lesions may be due to biotin deficiency resulting from the use of ovalbumin as the protein source.