B-cells

Question 1

b cell

Answer 1

1) WBC shows B cell number
2) humoral adaptive immunity
3) membrane bound AB structure known as BCR which are similar in structure to secreted Abs

Question 2

b cell development

Answer 2

1) initial development starts in bone marrow in primary lymphoid tissue
2) leave bone marrow and travel via circulation to spleen and lymph nodes (secondary lymphoid tissue)

Question 3

stomal cells in the bone marrow

Answer 3

1) they communicate with maturing B cells via receptor ligand interactions
2) trigger intracellular signaling that activate various TFs
3) promote gene expression specific to each step of the B cell maturation process

Question 4

as a result of TFs activity

Answer 4

1) various genes are activated and inactivated as B cells undergo maturation
2) recombination activating gene 1 and 2 (RAG1 and 2) proteins drive the rearrangement of sections in the genes responsible for immunoglobulin production
3) when this is complete, immature B cells leave the bone marrow and travel to secondary lymphoid tissue to continue their maturation

Question 5

immunoglobulin genes

Answer 5

1) have a unique structure for vast antibody diversity
2) the genomic structure of the heavy and light chain genes include multiple variable, diversity, and joining segments which are selected and pliced together

Question 6

RAG 1 and RAG2

Answer 6

1) drive a somatic recombination that rearranges genomic DNA
2) VDJ recombination is responsible for vast array of Abs generated by B cells
3) 2 heavy and 2 light chains

Question 7

isotypes

Answer 7

1) subtypes of antibodies
2) Fc constant region isotypes
3) IgM
- first Abs produced during infection (many are made)
4) IgG
- memory B cells make it later
- elevation means low level replication of EBV (chronic)

Question 8

B cell function

Answer 8

1) antibodies play multiple roles in neutralizing pathogens and toxins

Question 9

initial testing for B cell autoreactivity

Answer 9

1) after spleen and lymph notes
2) they become exposed to self and non self antigens (already tested in bone marrow)
3) APCs help B cells develop
- if bonds strongly with self protein, it is bad and apoptosis
4) if it bonds weakly to self, they receive signaling that blocks their ability to go with clonal expansion (die eventually)

Question 10

B cell function

Answer 10

1) membrane bound Abs are BCR
2) secreted immunoglobulins are Abs
3) antigen binding domain is the same in both
- constant region is varying structure between the BCR and Abs
4) multiple ABs can bind an antigen and crat larger complex to bait macrophages and activate complement

Question 11

Abs bind due to

Answer 11

1) noncovalent forces
- van der waals
- electrostatic
- hydrophobic
- ionic
2) each AA in the binding domain has unique functional groups which determine which forces that can interact
3) frameshift mutations

Question 12

in follicular structures

Answer 12

1) B cells are exposed to non self antigens
2) when there is a match between BCR and non self antigen, the B cell migrates to interfollicular zone
3) T helper cell (CD4+) which completes its activation
4) activated B cells differentiate into germinal center B cells, plasma cells, and memory B cells (clonal expansion)
5) memory and plasma cells exit follicle and migrate to periphery

Question 13

CBC

Answer 13

1) CBC with differential quantifies the total WBC count and provides a breakdown of cell types
2) for patients with active infections, value can be in the 20k range
3) if a cell type is individually elevated, can mean lymphoma or myeloma