Nitroblue tetrazolium test is used for:

Nitroblue tetrazolium test (NBT) is the original & most widely used test for chronic granulomatous disease. It is negative in chronic granulomatous disease & positive in normal individuals. It is used for detcting the production of reactive oxygen species in the phagocytes. Chronic granulomatous disease is a disorder of phagocytes. Patients suffering from chronic granulomatous disease have leucocytes that ingest microbes normally but lack the fully functional NADPH oxidase syst required to produce the superoxide anion. In these patients there is no respiratory burst due to lack of one of four NADPH oxidase subunits in neutrophils. Thus, these patients are not able to generate superoxide, H2O2 and OH- ions (free radicals). (Hence they are able to kill the bacterias). Leucocytes from the patients of chronic granulomatous disease fail to reduce nitroblue tetrazolium di phagocytosis. This propey has been used as a screening method for the diagnosis of chronic granulomatous disease.Ref: Robbins 8th Ed Page 55.