A 4-year-old female is found to have unusual susceptibility to infections by catalase-producing organisms. This patient likely has a problem with the function of which of the following cell types?
1.B cells
2.T cells
3.Natural killer cells
4.Neutrophils
5.Eosinophils
sol:
Patients with chronic granulomatous disease, in which neutrophils are dysfunctional, have increased susceptibility to infection by catalase-producing organisms.
Chronic granulomatous disease (CGD) is characterized by a deficiency of neutrophil NADPH oxidase. Normally, NADPH oxidase generates reactive oxygen species in the neutrophil which are converted into the antibacterial hydrogen peroxide. Individuals whose neutrophils cannot produce their own hydrogen peroxide are thus highly susceptible to bacteria that break down hydrogen peroxide (catalase-positive organisms). Examples of catalase positive organisms include S. aureus, E. coli, Pseudomonas, and Aspergillus.
Illustration A is a flowchart showing the steps of diagnosis for a suspected primary immunodeficiency.