history of pyogenic infections - okt3

[ArchivalUser]

thanks hope to pass

[ArchivalUser]

Good explanation hope to pass with 99, I just login


The correct answer is D. This patient has chronic granulomatous disease (CGD), which is associated with a
defective intracellular respiratory burst in phagocytes. CGD consists of a group of heterogenous disorders of
oxidative metabolism affecting the pathways required for hydrogen peroxide production by phagocytic cells. It
is inherited as an X-linked or autosomal recessive trait. Normally, stimulated phagocytic cells undergo a
respiratory burst consisting of increased oxygen consumption leading to the generation of intracellular
hydrogen peroxide and superoxide radicals. The hydrogen peroxide and superoxide radicals are required for
the killing of ingested intracellular organisms. The reaction is catalyzed by an NADPH oxidase that appears to
be defective in the phagocytes of patients with CGD; the enzyme defect appears to be due to inherited
mutations in the genes encoding cytochrome subunits. In CGD patients, the engulfment process by the
phagocytic cells is normal; however, the pathogenic organism will not be killed, but will persist within the cell.
The patients suffer from infections with organisms that are normally considered of low virulence (e.g.,
Staphylococcus aureus, Aspergillus, Candida, Escherichia coli, and Serratia marcescens). The nitroblue
tetrazolium (NBT) test is used to screen for CGD.

B cells (choice A) are responsible for antibody-mediated immunity, and the immunoglobulin levels in this
patient were normal.

Chemotaxis (choice B) is important in the migration of the phagocytic cell toward the site of infection, not in
intracellular killing.

IgG subclass 2 (choice C) is the most important immunoglobulin in the protection against encapsulated
organisms.

T cells (choice E) are important in the host response to viruses, fungi, and intracellular bacterial organisms.
The patient was immunized normally (including the live, attenuated MMR vaccine), making T-cell dysfunction
unlikely.