Staining of Eosinophils with Nitroblue Tetrazolium in Patients with Chronic Granulomatous Disease

Abstract

The nitroblue tetrazolium (NBT) test is the primary screening test for chronic granulomatous disease (CGD). Neutrophils and other phagocytic cells readily reduce NBT to blue formazan after oxidative stimulation whereas CGD cells remain colorless. In the present study purified eosinophil populations were obtained from CGD patients and normals by exposing peripheral blood to the peptide N-formyl-methionyl-leucyl-phenylalanine and then centrifuged over a discontinuous Percoll gradient. The eosinophils were then incubated in 0.1% NBT (37 degrees C, 15 min) with either phorbol myristate acetate or buffer alone (HEPES with calcium and magnesium). Blue staining characteristic of NBT reduction occurred in the phorbol myristate acetate-stimulated eosinophils of half (4/8) of the CGD patients tested. The staining was most intense between the nuclear lobes of the eosinophil with little staining near the cell periphery. The staining pattern was present in 75.5 +/- 5.3% of the purified eosinophils in those patients in which the phenomenon occurred and was reproducible in the same patients over a 6-month period. Eosinophils from normal individuals tested with NBT and phorbol myristate acetate showed intense staining over the entire cell cytoplasm as did normal neutrophils. Purified CGD eosinophils that did show the staining pattern were not able to produce superoxide (as measured by cytochrome C reduction) when stimulated by phorbol myristate acetate indicating the staining was probably not related to superoxide production. Patients with CGD have a mild eosinophilia (4.6 +/- 0.7% in 11 patients at the National Institutes of Health) and eosinophil staining may account for the small number of positive NBT cells reported in some patients.