Nitroblue tetrazolium test is used for ?
Phagocytosis In the previous discussion we have seen that with phagocytosis neutrophils gets activated and there is rapid burst of oxygen consumption and activation of hexose monophosphate shunt. The rapid burst occurs due to rapid activation of the enzyme complex NADPH oxidase which oxidizes NADPH and in the process reduces oxygen to superoxide anion (0,-). It catalyzes the reduction of oxygen to superoxide anion which is then conveed to hydrogen peroxide and other toxic oxygen products (011-) (free radicals). H.,02 then combines with myeloperoxidase and halide to form an effective antibacterial compound. (HOCC-) Chronic granulomatous disorder 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 system, required to produce the superoxide anion. In these patients there is no respiratory burst due to lack of one of the four NADPH oxidase subunits in neutrophils. Thus, these patients are not able to generate superoxide, H202 and OH- ions (free radicals). (Thus the), are not able to kill the bacterias). Leucocytes from the patients of chronic granulomatous disease fail to reduce nitroblue tetrazolium during phagocytosis. This propey has been used as a screening method for the diagnosis of chronic granulomatous disease. More on chronic granulomatous disease:- Inheritence - X linked (more common) - Autosomal recessive There is increased incidence of bacterial infection. The bacterias involved in recurrent infections are catalase positive pyogenic pathogens such as staphylococci and colifonns. Catalase negative pathogens are handled normally There is excessive inflammation with granuloma formation. Clinical features are ? - Suppurative lyrnphadenopathy - Gingivitis - Aphthous ulceration - Seborrhic dermatitis - Obstruction of gastrointestinal or genitourinary system - Autoinimune complications - Immune thrombocytopenic purpura - Juvenile rheumatoid ahritis Tests for diagnosis Nitroblue tetrazolium test Dihydrorhodamine (DHR) oxidation test Immunoblot for NADPH oxidase components
Phagocytosis
Complement
T cell
B cell