Cryptogenic pulmonary eosinophilia.

The clinical and immunological features of fifteen cases of cryptogenic pulmonary eosinophilia are reported. There were ten women (mean age 35.4 years) and five men (mean age 42 years). Eight gave a previous history of asthma and seven had none. Thirteen of the fifteen patients had negative skin test to common allergens. Many features of a systemic illness were present in the asthmatic and non-asthmatic groups including anaemia, weight loss, fever and a grossly raised ESR. An absolute polymorphonuclear leucocytosis was frequent as well as the obligatory increase in blood eosinophils used as one of our criteria for inclusion. Hepatomegaly (three cases), splenomegaly (four cases) and hilar node enlargement (one case) were seen in the group without asthma. Evidence of renal involvement or necrotizing vasculitis was notably absent and the response to small doses of corticosteroids was dramatic. Immunologically the striking feature was a disproportionate increase in blood eosinophils compared with only minor elevations in the total serum IgE levels. This stands in contrast to patients with bronchopulmonary aspergillosis and helminth infestation. Studies of cytophilic antibodies using histamine liberation after challenge with antibodies to immunoglobulin sub-classes in six patients showed a marked increase in IgG2 and lesser increases of IgE and IgG3. No evidence of antibodies specific to A. fumigatus was found. The amount of cytophilic antibody was also in contrast to that found in bronchopulmonary aspergillosis.