Nitroblue-Tetrazolium Test

Chronic granulomatous disease is most frequently aused by genetic deficiency of NADPH oxidase in the PMN. Patients are susceptible to infection by catalasepositive organisms such as Staphylococcus aureus, Klebsiella, Escherichia coll, Candida, end Aspergillus, k negative nitroblue tetrazolium test is useful in confirming the diagnosis. 

Thyroid 1 uptake may be decreased. False-negative results with the nitroblue-tetrazolium test for bacterial infection. Dexamethasone, given for cerebral edema, may alter the results of a brain scan (decreased uptake of radioactive material). 

Dioxane proved to be the most suitable solvent for extracting the formazan formed in the nitroblue tetrazolium test (Muller et al. 1981). At 85 °C dioxane completely extracted nitroblue tetrazohum (absorption maximum at X, = 580 nm, absorption coefficient = 0.0256 ml X nmol X cm" ) from the cell pellet within 15 min, and nitroblue tetrazohum diluted in dioxane was sufficiently stable. As a possible aqueous contamination under conditions of an acid pH caused a slower decrease of the optical density of the extract than did pure water, 1 N HCl as washing agent to remove remaining nitroblue tetrazolium from the cell pellet is recommended. 

The Nitroblue tetrazolium test (NET), as applied to the infective problems (30) presents an intriguing development. This phenomenon of reduction of colorless Nitroblue tetrazolium to blue/ black forazan by the neutrophil of normal man in vitro (7) was applied to the phagocyte in vivo during bacterial infection in infants by Park in 1968 (46). Later confirmation was obtained with adults (27,41) in bacterial infection and in fungal infection (5,46). 

The most common laboratory diagnostic is the nitroblue tetrazolium (NBT) test which detects impaired function, inability to produce reactive oxygen species, in isolated leucocytes. Female carriers may be identified by this test. 

Principle The respiratory burst of phagocytic cells can be assessed by incubating a suspension of the cells in an isotonic solution of the yellow oxidised nitroblue tetrazolium (NBT) dye. During this process, the soluble dye interacts with the cytoplasmic components associating with the oxidant species generated. Although the NBT test is not a specific marker for superoxide production, NBT reduction by activat-... 

In this test, p-hydroxybutyrate in the presence of NAD is converted by P-hydroxybutyrate dehydrogenase to acetoacetate, producing NADH. Diaphorase catalyzes the reduction of nitroblue tetrazolium (NBT) by NADH to produce a purple compound and its absorbance is read in a special meter that provides a digital readout. 

A Mn11 complex with an all-nitrogen first-coordination sphere was reported in 1996 to be a competent MnSOD mimic (436). In this case the complex is composed of two meridonally binding 2,6-bis(benzimi-dazol-2-yl)-pyridine ligands. When tested against the NBT system, this complex was reported to exhibit an LCB0 value of 0.72 pmol dm 3. This level of activity is comparable to that observed for the other systems tested by the nitroblue tetrazolium system. 

The ability of a test compound to induce differentiation of HL-60 cells (derived from a patient with acute promyelocytic leukaemia) is also an important assay of retinoid activity [91-93]. HL-60 cells do not produce superoxide anions upon stimulation by agents like TPA. Differentiated HL-60 cells, however, do produce these anions upon similar stimulation. The presence of these anions can be monitored because of their ability to reduce the yellow nitroblue tetrazolium (NBT) to the water insoluble blue-black formazan. Determination of the concentration (ED50) which results in differentiation of 50% of the cells is the measure of the anti-APL activity of the retinoid. Morphological maturation of the cells can also be checked. 

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