X-linked hyper IgM syndrome, resulting in high levels of serum IgM and low level

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Question
X-linked hyper IgM syndrome, resulting in high levels of serum IgM and low levels of serum IgG, is caused by a defect in CD40L expression. The specific immune event that would be prevented by a defective CD40L would be
Options
A. activation of B cells by T-independent antigens
B. failure of B cells to provide co-stimulation for Th2 activation
C. failure of Th2 cells to provide co-stimulation for B cell isotype switching
D. failure of Th2 cells to provide co-stimulation for B cell proliferation

Correct Answer

failure of Th2 cells to provide co-stimulation for B cell isotype switching

1. Difficulties with somatic gene therapy arise from all of the following except
Options
A. GVHD caused by mature T cells in the transplanted cells
B. inserting a gene so that it will function properly
C. limited life span of more mature hematopoietic cells
D. transducing genetic material into stem cells

3. Combined cellular and humoral immune deficiencies result from lack of all of the following except
Options
A. a thymus
B. class II MHC
C. HIV infection of CD4⁺ T cells
D. transporter of antigen peptides (TAP)

8. Chronic granulomatous disease results from a failure to perform oxidative burst. This deficiency would be most likely to interfere with
Options
A. CTL killing of viruses
B. dendritic cell activation to become a mature APC
C. infected cell processing of virus peptides
D. macrophage intracellular killing of bacteria

9. Infants are most susceptible to bacterial infection due to low circulating levels of IgG
Options
A. in utero (before birth)
B. at 0-3 months of age
C. at 3-12 months of age
D. at 12-24 months of age

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