In which of the following conditions is negative nitroblue tetrazolium dye test result seen?
High-Yield Explanation
Chronic granulomatous disease (CGD) has a defective NADPH oxidase activity with recurrent infection and granuloma formation affecting gastrointestinal or genitourinary tract. CGD can be diagnosed with the following tests:
Nitroblue-tetrazolium (NBT) test: It is negative in chronic granulomatous disease and positive in normal individuals. This test depends upon the direct reduction of NBT by superoxide free radical to form an insoluble formazan. This test is simple to perform and gives rapid results, but only tells whether or not there is a problem with the PHOX enzymes, not how much they are affected.
Dihydrorhodamine (DHR) test: In this test, the whole blood is stained with DHR, incubated and stimulated produce superoxide radicals which reduce DHR to rhodamine in cells with normal function.
Cytochrome C reduction assay is an advanced test that tells physicians how much superoxide a patient’s phagocytes can produce.