11. A selective IgA deficiency would be expected to result in problems with

A. bacterial infections
B. infections following dental work due to bacteria entering the bloodstream
C. mucosal pathogens
D. pathogens which can survive inside macrophages

12. Combined cellular and humoral immune deficiencies result from lack of all of the following except

A. a thymus
B. class II MHC
C. HIV infection of CD4⁺ T cells
D. transporter of antigen peptides (TAP)

13. An example of an immunodeficiency disorder is

A. thyroiditis
B. rheumatic fever
C. systemic lupus erythematosus
D. AIDS

14. Bone marrow given to an infant with SCID must

A. be irradiated to eliminate GVHD
B. contain mature T cells that can begin making immune responses immediately
C. come from a donor that shares some MHC alleles with the recipient
D. come from one of the child’s parents

15. 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

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