Immunocytochemical Study for Lactalbumin in Alveolar Macrophage of Human Milk Aspirated Mouse

ABSTRACT

PURPOSE: Aspiration of foreign material into the lungs can cause acute or chronic pulmonary diseases. It is difficult to detect small amounts of aspiration due to the lack of safe, sensitive and specific diagnostic tests. Recently, in animal or human studies, it has been reported that immunochemistry for lactalbumin can be used to detect the minimal aspiration. So, the authors' investigation was designed to determine whether human milk phagocytized alveolar macrophages can be detected in human milk aspirated mice. METHODS: Sixty four male mice, 6-8 weeks old and 30-40 gm weighing, were used for this study. About 0.05 mL of human milk or normal saline were given intranasally once per day for 1 day or 3 days. Under anesthesia with ketamine and xylazine, the trachea of each mouse was cannulated with an 18G Jelco needle and then, each mouse's lungs were lavaged three times with 0.5 mL of phosphate buffer solution at 2, 8, 24, and 48 hours after the last milk or normal saline instillation. Cells in bronchoalveolar lavage fluid were stained with Oil Red O and immunocytochemistry for alpha-lactalbumin. RESULTS: Immunocytochemical reactivity for alpha-lactalbumin or lipid-laden alveolar macrophages were not observed in the normal saline aspirated groups. Immunocytochemical reactivity for alpha- lactalbumin were observed in the human milk aspirated groups. They showed a peak at 8 hours and decreased markedly at 24 hours but persisted even at 48 hours after aspiration. Immunocytochemical stain positive alveolar macrophages were noted similarly in number between single and multiple aspiration groups. CONCLUSION: These observations suggested that alveolar macrophages for lactalbumin could be more easily detected on immunocytochemistry than Oil Red O stain, and immunocytochemistry could be used as a sensitive and specific diagnostic test for the detection of human milk aspiration.