Answers (Grade A+)
What role does B cells play in? -
correct answer ✅- Innate and adaptive immunity
What are the 3 known subsets of B cells and what immunity do
they play in? -
correct answer ✅- B1: Innate immunity
- B2 (conventional): Adaptive Immunity
- Marginal Zone B cells: Innate and Adaptive immunity
What subsets is B-1 B cells divided into and what do they both
contain? -
correct answer ✅- B-1a expressing protein CD5
- B-1b that do not express CD5
- Both are high in IgM
- Important to know B-1 B cells sometimes express CD5 (marker for
T cells)
Describe B-1 B cells and their location? -
correct answer ✅- Long-lived and self-renewing
- Develops early in ontogeny from fetal omentum and liver
- After birth, stems cell for B-1 are NOT present in bone marrow
,MIMG 185 Final Exam Questions &
Answers (Grade A+)
- In adults, they are found predominately in peritoneal and pleural
cavities
- Rare in spleen and absent from lymph node and peripheral blood
Describe the variability of the B-1 B cells and what they produce -
correct answer ✅- Limited V region repertoire
- Lots of self-reactivity
- Recognition of bacterial antigens (phosphorylcholine)
- Broad specificity and low affinity
- Produce specifities encoded in germline with no N region insertion
and little somatic mutation
- Produce large amounts of antibody (>50% of all antibodies in
serume)
- Responsible for majority of non-immune serum IgM and
constribute to resting IgA
- If you immunize your reaction, there will be IgM present that is
non-immune cause of B-1 B cells
What type of responses does B-1 B cells have and do they require T
cell help? -
correct answer ✅- Does not require T cell help
,MIMG 185 Final Exam Questions &
Answers (Grade A+)
- TI-2: make antibody response to polysaccharide Ags found on
bacteria
- Plays role in innate response to infection (Abs mostly germline
encoded)
- Rapid response: Makes Abs within 48 hours of antigen exposure
(due to bacterial antigen)
- Without T cell help, do not isotype switch (although some IgA)
and no memory
What is the origin of B-1 B cells and what role does it play in
autoimmune disease? -
correct answer ✅- Hypothesized to be primitive B cells
- In mice, at birth predominately B-1 but later B-2 dominates
- Abundant in autoimmune disease (specficity is often self-reactive)
- B-1 cells origin for human chronic lymphocytic leukemia, typically
express CD5
B-2 B cells arise from where and how do they generate and play a
role in the immune response? -
correct answer ✅- Principle B cells in secondary lymphoid organs
(spleen, lymph nodes)
- Arise from fetal liver and bone marrow in adult
, MIMG 185 Final Exam Questions &
Answers (Grade A+)
- Stem cells continually generate
- Principal B cells in adaptive immune response
Explain the variability of B-2 cells and if they need T cell help or
not? -
correct answer ✅- Have extensive variable region repertoire
generated somatically
- Requires T cell help, therefore have isotype swtich and memory
- Recirculates through B cell rich lymphoide follicles
- TD antigen responses in germinal center
Where are Marginal zone (MZ) B cells found and what role do they
play? -
correct answer ✅- Originate in bone marrow from same
precursors as B-2 B cells
- Found in marginal zone of the spleen
- Participate both in TI and TD antibody responses
- Contribute to natural IgM present
- Memory B cells also found in marginal zone
- Contain somatic mutations (like B-2)
- Response to blood-borne antigens