S3M1 Microbiology Sloma B Cell Biology

Front 1

What kinds of antigens do B cells recognize?

Back 1

Proteins, carbs, lipids and nucleic acids

Front 2

What role do antibodies play in the immune response?

Back 2

complement fixation
coating and pathogen opsonization
-activation of NK cells

Front 3

The B cell receptor (antibody molecule) is surface bound and complexed with what two intracellular signaling proteins?

Back 3

Iga (alpha)
IgB (beta)

These molecules help the B cell receptor with intracellular signalling

Front 4

Where do B cells eliminate self reactive clones?

Back 4

In the bone marrow

Developing B cells get their receptors in the bone marrow and if those receptors recognize self antigens they are eliminated.

Front 5

Where are B cells activated by antigen?

Back 5

In the secondary lymphoid tissue.

These are mature yet unstimulated B cells to this point.

Front 6

B cells grow up in the following fashion:
Stem cell>Pro B cell>Pre B cell>Immature B cell

Which point does it gain a CD 19 and why is this important?

Back 6

When a B cell is a pro-B-cell, it gains expression of the CD19 which is a marker to see if B-cell is good and not F'd up.

Front 7

Stem cell>Pro B cell>Pre B cell>Immature B cell?

When does the following happen:
-Gain CD19
-Begin rearrangement of Heavy chain
-Begin rearrangement of light chain
-Express BCR on surface with Iga and IgB

Back 7

A cell gains CD19 and begins rearrangement of the heavy chain as a Pro-Bcell

A cell rearranges light chain at pre-B cell

Expresses BCR with Iga and IgB as an immature B cell

Front 8

What constant sequence encodes for IgM?

Back 8

There is a Cmu region on the heavy chain locus that encodes IgM

Front 9

What is the sequence for Light chain?

What is the sequence for the heavy chain?

Back 9

Light chain = VJ
heavy chain= VDJc

Front 10

Rearrangement and recombination requires what genes?

Back 10

RAG 1, RAG 2 and terminal deoxynucleotidy transferase (TdT).

Front 11

When a heavy chain is made in the proB cell stage, how is it tested without a light chain yet present?

Back 11

It uses a surrogate LC which acts for teh unformed light chain so the B cell can test the heavy chain.

Front 12

What is allelic exclusion?

Back 12

Expression stops when a functional pre BCR is expressed on the surface. This prevents rearrangement of the other heavy chain and guarantees only one specificity for the entire B cell.

Front 13

What if no allelic exclusion?

Back 13

Without allelic exclusion, B cells would have many BCR with different specificities. This would compromise the cells ability to reach threshold by binding enough Antigen for a T cell to recognize.

Front 14

What Surface Ig does an immature B cell express?

What about a mature B cell?

Back 14

Immature B cell only IgM

Mature B cell expresses IgD and IgM

Front 15

Put these things in order:
-Negative selection
-Light chain rearrangement
-Exit from the bone marrow
-Heavy chain rearrangment
-Expression of surface bound IgM

Back 15

1: Heavy chain rearrangment
2: Light chain rearrang
3: Negative selection
4: Expression of surface bound IgM
5: Exit from bone marrow

Front 16

This is the process by which Immature B cells with self reactive B cell receptors can attempt to re-arrange their light chain.

Back 16

Receptor editing

If the B cell fails gain=apoptosis (clonal deletion)

Front 17

Not all self antigens are expressed in Bone marrow. Self reactive immature B cells can recognize self antigen in periphery and either die by apop or what...

Back 17

Become incapable of future activation (anergic)

Front 18

Describe the process of B cell maturation (*start from exiting from the bone marrow).

Back 18

Bone marrow-->blood and lymph-->secondary lymphoid tissue--> receives chemokines to survive-->exits secondary lymphoid tissue-->Exits as a mature B cell

Front 19

How do you know if a B cell is mature or not?

Back 19

Maturation of B cells causes an Ab isotype switch to IgD.

Front 20

Once ACTIVATED, B cells will clonally divide and proliferate. What are the options?

Back 20

Activated B cells can either divide into plasma cellsor memory cells.

Front 21

Some activated B cells immediately become plasma cells to pump out antibody. IgM is no longer ______-________ but ___________.

Back 21

Igm is no longer surface-bound but is secreted.
Plasma cells lose their surface IgM molecules and stops MHC class II expression.

Reason being they are no longer interested in working with T cells.

Front 22

Activated B cells have three specialized methods of improving antibody molecules...

Back 22

-Somatic hypermutation
-affinity maturation
-isotype class switch

Front 23

This is a Nucleotide substituion at a high rate to create an antibody that has a higher affinity for the antigen.

Back 23

Somatic hypermutation

This is a random rearrangment of the variable region of the heavy and light chains. This increases Fab variability.

Front 24

This is a process in which the hypermutated BCR clones compete for the antigen. The winner lives.

Back 24

Affinity maturation

Front 25

This is when the a change in the CONSTANT region where segments of the gene for the heavy chain locus are removed.

Back 25

This is isotype switching.

Rearranged V regions can be used with other C genes

Front 26

שְׁלֹשָׁה

Back 26

three (plural)

Front 27

What secondary signal drives B cell proliferation and division?

Back 27

CD40:CD40L interaction

This only occurs with B cells and T cells that recognize the same antigen

Front 28

Some bacterial antigens can stimulate naive B cells in the absence of T cell help. What are some factors that encourage this?

Back 28

-Very repetative polysaccharides
-Polymeric proteins
-Lipopolysaccharides

The secondary signal actually comes from the antigen itself

Front 29

What are the advantages and drawbacks of thymus independent antigens?

Back 29

Bonus:
Fast response

Drawback:
No class switching (IgM only)
Antibody repertoire against antigen is limited.
No affinity maturation