Immunologic Studies in Cow's Milk-induced Pulmonary Hemosiderosis

Abstract
Summary: Antibodies to cow's milk proteins (CMP) were studied by radioallergosorbent tests to determine the quantity and immuno-globulin class of these antibodies in nine patients with precipitins to cow's milk. Three of these patients had pulmonary hemosiderosis (PH); in one other patient pulmonary hemosiderosis was suspected, but not proven. Three patients had non hemosiderosis chronic lung disease and two had other diseases. Age-matched control subjects were also studied. The quantity and immunoglobulin class distribution of antibodies to CMP were similar in all patients; the quantity of anti-CMP antibody was significantly greater in patients than in control subjects (P < 0.001). In addition, complement-fixing antibody to CMP was not detected in either patients' or controls' sera. Lymphocyte responses to CMP were studied in three patients with PH, three individuals with other manifestations of milk hypersensitivity (positive controls), and nine negative control subjects. Patients and positive control subjects responded to CMP with greater tritiated thymidine incorporation than the negative control subjects (P < 0.05). However, no significant difference in response to CMP was observed between the PH patients and the positive control subjects. Antibodies to human lung tissue were studied in the sera of all patients with PH and two negative control subjects. Antibodies to human lung and rat lung were detected in one patient with PH. Speculation: We have been unable to demonstrate any unique immunologic mechanism associated with milk-induced PH in the patients studied. However, these studies do not completely rule out the role of these immune mechanisms as it is possible that the antigen or antigens responsible for the relevant reactions may result from partial degradation of cow's milk protein and were not studied. Alternatively, increased availability of antigens maybe important, which might result from excessive gastrointestinal absorption of intact cow's milk proteins. Furthermore, the possibility exists that unique antigens may be present in the lungs of patients with PH which cross-react either with antibodies to CMP or sensitized cells.