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The NBT-test is a technique particularly used in its stimulated variant for testing granulocyte metabolism and in this capacity it is an integrated part of the test programme for differentiating neutrophilic dysfunctions. Its sphere of application is the diagnosis of progressive septic granulomatosis. The variety of the methods used makes it difficult to compare the results described by the various authors. Therefore, standardization is urgently necessary. A differentiation of bacterial and non-bacterial infections as well as of other febrile diseases is not possible with the unstimulated test. Investigations of the longitudinal section, however, allow the activity of the disease to be evaluated (with initially high numbers of granulocytes being positive in the nitroblue tetrazolium test).

The available literature on the nitroblue tetrazolium reduction test is reviewed. The mechanism of this test is poorly understood. There are two basic methods of performing the test, namely, the stimulated and the spontaneous methods. However, the test procedure has not been standardized, and numerous modifications have ensued resulting in a number of technics. The stimulated test has proved to be valuable for screening patients or carriers with chronic granulomatous disease of childhood. It is one of the useful tests in studying neutrophil dysfunction. On the other hand, extensive accumulated data indicate that this test, be it stimulted or spontaneous, cannot be relied upon as an absolute test to differentiate bacterial from nonbacterial infectious disease as there have been numerous false-positive and false-negative results. When this test is used, the result should be interpreted in the context of other laboratory test results and the clinical picture of the patient. Preliminary data indicate that in certain diseases, if the initial test is positive in a particular patient, it may be useful as one of the follow-up tests to ascertain the activity of the disease process.