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Diagnosis of chronic granulomatous disease
Last reviewed: 23.04.2024
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Diagnostics
Diagnosis of chronic granulomatous disease is based on the evaluation of the functional activity of phagocytes. The following tests are used:
- Nitrosine tetrazolium reduction test (NST test). Normally, when the yellow dye nitrous tetrazolium (ICT) is absorbed by the phagocytes, their metabolic activity increases, while the NST oxidizes, and the products of this reaction are dyed blue. If the metabolism of phagocytes is disturbed, the intensity of blue staining decreases.
- Chemiluminescence of neutrophils. The oxidation of the substrate is accompanied by the emission of ultraviolet light or fluorescence, the intensity of radiation can be judged on the functional activity of phagocytes.
- Evaluation of phagocytic activity: the ability of phagocytes to destroy catalase-positive bacteria in vitro.
- Genetic examination of patients and their families in the detection of abnormalities in the functional activity of phagocytes.
Definition of types and subtypes of chronic granulomatous disease
To determine the types and subtypes of chronic granulomatous disease, as a rule, immuno-blotting using antibodies to all 4 components of NADP oxidase is used. If one of the cytosolic components (p47 phax or p67 phax ) is absent in the blot, this indicates a mutation in the corresponding gene, whereas in the absence of one of the membrane components (gp91 phax or p22 phax ), the other is also not determined. Subunits stabilize each other for complete maturation and expression. A number of investigators have used cytoplometry using anti-cytochrome p558 antibodies to determine gp91 phax / p22 phax on the surface of neutrophils. Ultimately, the diagnosis is confirmed by the detection of the mutation of the corresponding gene.
Prenatal diagnosis of chronic granulomatous disease
Before it became possible to use molecular genetic technologies, prenatal diagnosis of chronic granulomatous disease was carried out by determining the NADP-oxidase activity of blood neutrophils, fetal cord sampling was performed by fetoscopy at the 16-18th week of gestation. DNA analysis of amniotic fluid or chorionic villus cells is currently being conducted to search for specific gene defects by Southern blotting, polymerase chain reaction, and restriction fragment length polymorphism, which is a more reliable method and makes it possible to diagnose at earlier stages of pregnancy.
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