Eosinophil cationic protein and immunoglobulin levels in bronchoalveolar lavage fluid obtained from patients with chronic eosinophilic pneumonia

In chronic eosinophilic pneumonia (CEP), histopathological evidence exists for the degranulation of eosinophils and the release of various toxic proteins. In vitro studies have demonstrated the degranulation of eosinophils in response to aggregated and complexed immunoglobulins. The aims of this study were to investigate: 1) whether the eosinophil cationic protein (ECP) and immunoglobulin (Ig) levels in bronchoalveolar lavage (BAL) fluid from patients with CEP are increased compared to those of healthy controls; 2) and whether a relationship is present between immunoglobulin levels and ECP levels in BAL fluid from patients with CEP. The BAL from 12 patients with CEP was selected, retrospectively, from all BAL analyses performed in our centre between 1986 and 1992. ECP levels were measured using a radioimmunoassay in BAL fluid of patients with CEP and 10 healthy controls. ECP levels and immunoglobulin levels in BAL fluid from patients with CEP were found to be elevated compared to controls (p < 0.001). A relationship was found between IgA levels and ECP levels in BAL fluid from patients with CEP (r = 0.72; p = 0.043). In conclusion, eosinophil cationic protein and immunoglobulin levels were found to be increased in bronchoalveolar lavage fluid from patients with chronic eosinophilic pneumonia. The relationship found between immunoglobulin A levels and eosinophil cationic protein levels may suggest that immunoglobulin A could be involved in the degranulation of eosinophils in chronic eosinophilic pneumonia.