Question

1. Multiple choice:
Self-reactive B cells can be eliminated from the
repertoire at several stages of B cell maturation, including immature B cells that have already emigrated from the bone marrow into the circulation. This latter stage of tolerance induction is critical because:
A. Not all self-antigens are expressed or present in the bone
marrow during B cell development.
B. Immature circulating B cells are more sensitive to antigen stimulation than the developing B cells in the bone marrow.
C. Receptor editing is not a perfect process and some self-reactive B cells may fail to be eliminated in the bone marrow.
D. Circulating immature B cells do not encounter tissue-specific antigens in peripheral organs and tissues.
E. Immature B cells are trapped in the bone marrow by strong B-cell receptor cross-linking.

2. Multiple choice:
Individuals that overexpress the cytokine BAFF
show increased susceptibility to autoimmune diseases such as Sjögren’s syndrome, a disease that targets the exocrine glands that produce saliva, tears, and other bodily secretions. If one examined the circulating antibodies in these patients, one would expect to find:
A. Increased development of B cells in the bone marrow
B. A failure of receptor editing of immunoglobulin light chain genes in the bone marrow
C. An increased rate of immature B cell export from the bone marrow
D. Reduced B-cell receptor signaling following strong cross-linking of the receptor
E. An increased number of circulating mature autoreactive B cells

3. Short answer:
Marginal zone B cells are thought to represent a lineage of cells important in rapid responses to blood-borne antigens. What are the two characteristics of these cells that indicate this function?

Answer 1