PCB 3233 - IMMUNOLOGY EXAM 3 NEWEST ACTUAL

PCB 3233 - IMMUNOLOGY EXAM 3 NEWEST ACTUAL /

QUESTIONS AND ANSWERS VERIFIED/GRADED A+

*B-1 cells* vs. B-2 cells (know the differences). Which is also

called a CD-5 B cell? - ----Answers----*B-1 cell:* (aka CD5

B-Cell)

- *First Produced:* Fetus

- *N regions in VDJ:* Few

- *V regions:* Restricted

- *Location:* Peritoneal and Pleural Cavities

- *Renewal:* Self-Renewing

- *Ig Production:* High

- Isotypes Secreted:* IgM > IgG

- Required for T-Cell Help:* No

- Somatic Hypermutation:* Low-None

- Memory Development:* Little or None

Extra Info:

• cells have little or no IgD on surface
• 5% in humans
• most active in prenatal period
• TdT not expressed in early prenatal period
• low affinity
• less diverse 1 / 4

• Adult population of B1 cells is maintained by the division of

existing B-1 cells at site in periphery circulation.

B-1 cells vs. *B-2 cells* (know the differences). Which is also

called a CD-5 B cell? - ----Answers----*B-2 Cells:*

- *First Produced:* After Birth

- *N regions in VDJ:* Extensive

- *V regions:* Diverse

- *Location:* Secondary Lymphoid Organs

- *Renewal:* Placed from Bone Marrow

- *Ig Production:* Low

- Isotypes Secreted:* IgG > IgM

- Required for T-Cell Help:* Yes

- Somatic Hypermutation:* High

- Memory Development:* Yes

Extra Info:

• High affinity
• more diverse

When would you expect to find RAG 1 and 2 being expressed and not being expressed? - ----Answers----*Expressed* = Late Pro-B Cell

• while it rearranges the heavy (late pro) and the light (small

pre) *Not Expressed* = Small Pre-B Cell 2 / 4

• while it rearranges the heavy (late pro) and the light (small

pre)

CCL-19, CCl-21 and CXCL-13, what are they, where are they with respect to secondary lymphoid tissues and what effects

do they have on B-cells? - ----Answers----*Where:*

• CCL-21= attracts immature B-Cells to HEV
• CCL-21/CCL-19= attracts B-Cells into lymph node
• CXCL-13= attracts B-Cells into primary follicle
• CCR7 binds to B-cells

*What:*

• Interactions with follicular dendritic cells and cytokines

drives the maturation of immature B cells

*Effects:*

• Mature B cells recirculate between lymph, blood, and

secondary lymphoid tissues

What is BAFF and what role does is play in a B-cells life? What

cell secretes BAFF? - ----Answers----*Definition:*

• B-cell activating factor in the TNF family

*Function:*

• Promotes B-cell survival

*Secreted by:*

• Follicular Dendritic Cells
• Made by several cell types in secondary lymphoid organs and

is bound by the BAFF receptor on B cells. 3 / 4

Where does Central tolerance vs. peripheral tolerance take place? What is a centrocyte and where would you find it? What is a centrablast and where would you find it? - ----Answers--

--*Central Tolerance:*

• selection taking place in primary lymphoid tissue

*Peripheral Tolerance:*

• selection taking place in circulation

*Centrocyte:*

• Centroblast mature into non-dividing centrocytes that have

undergone Ig class switching and somatic hypermutation.

• Found in the light zone.

*Centroblasts:*

• Are large proliferating B cells.
• Found in the dark zone.

What are the light and dark zones of a germinal center and

what is found in each? - ----Answers----*Dark Zones:*

• The part of a germinal center in secondary lymphoid tissue

that contains dividing centroblasts (B-Cells and large proliferating B-cells (centroblasts)).

*Light Zones:*

• The part of a germinal center in secondary lymphoid tissue

that contains non-dividing centrocytes interacting with follicular dendritic cells (Centrocytes, Follicular dendritic cells, helper T cells, B cells).

• / 4