Chapter 6: Secondary Lymphoid Tissue: B and T Lymphocyte Activation

Question 1

Understand this image

Answer 1

Look through every part of image to ensure understand

Question 2

The costimulatory molecules B7-1 (CD80) and B7-2 (CD86) on APCs bind to what cell marker on the mature, naive T cell?

Answer 2

CD28 which in on switch

Question 3

Later in an immune response, B7 will preferentially bind to what receptor, effectively turning off the T-cell response

Answer 3

CTLA-4 or PD-1

Question 4

What are some CTLA-4 agonist drugs?

Answer 4

Abatacept
Belatacept

Question 5

Clinical use of abatacept?

Answer 5

rheumatoid arthritis

Question 6

Clinical use of Belatacept?

Answer 6

renal transplants

Question 7

Antagonists of CTLA-4?

Answer 7

ipilimumab

Question 8

Clinical use of ipilimumab?

Answer 8

melanoma and in clinical trials for several other types of cancer

Question 9

How does IL-2 release affect T helper cells and CD8 T cells? How are they expressed by each of these types of cells?

Answer 9

They help both types proliferate

They both have IL-2 receptors but helper T lymphocytes produce large amounts of IL-2

Question 10

What are superantigens?

Answer 10

viral and bacterial proteins that cross-link variable β domain of T cell receptor to an α chain of class II MHC molecule outside of the normal peptide binding groove

cross-linking activates cell and induces T cell activation and proliferation in the absence of antigen-specific recognition of peptides in the MHC class II groove

Question 11

What are the 3 major classes of helper T cells that arise from the same precursors Th0 cells?

Answer 11

• Th1
• Th2
• Th17

Question 12

Draw out the subsets of helper T cells, their pathways, functions and cytokines produced.

Answer 12

Subsetsof T Helper Cells

Question 13

Which type of T cells do T regs inhibit?

Answer 13

Th1 cell function

Question 14

What are the markers that are found on Tregs?

Answer 14

CD25 and transcription factor FoxP3

Question 15

What inflammation inhibiting cytokines do Tregs secrete?

Answer 15

IL-10 and TGF-B

Question 16

Which cells produce is strong response to tuberculoid leprosy?

Answer 16

Th1 cells

Question 17

Major symptoms of tuberculoid leprosy?

Answer 17

• intracellular pathogen with granuloma formation
• Some damage to skin and peripheral nerves, but the disease progresses slowly, if at all, and the patient survives

Question 18

What type of cells produce a strong response when a patient has lepromatous leprosy?

Answer 18

Th2 response is turned on, and cell mediated response is depressed

Question 19

Symptoms of lepromatous leprosy?

Answer 19

• diffuse acid fast staining throughout tissue
• much more severe presentation than tuberculoid
• ab production not protective

Question 20

What are the 2 categories of ag that B lymphocytes encounter?

Answer 20

Thymus- independent (TI)
Thymus- dependent (TD)

Question 21

Describe TI ag activated B lymphocytes.

Answer 21

Certain B lymphocytes can be activated by macromolecules such as lipids, polysaccharides, and lipopolysaccharides without having to interact with other T lymphocytes

Question 22

Describe immune response upon B lymphocyte activation by TI ag as opposed to TD ag.

Answer 22

immune response is generally weaker than the response to TD antigens,

resulting primarily in the
secretion of IgM ab and the absence of immunologic memory

Question 23

Describe TD ag.

Answer 23

Response to these molecules requires direct contact of the B cells with helper T cells are are influenced by cytokines secreted by these cells

Question 24

What are the 2 waves with which B lymphocytes activated by TD antigens are released?

Answer 24

Primary wave of activated B lymphocytes is comprised of strictly IgM secreting plasma cells which leave secondary lymphoid tissue shortly after activation.

Second wave: rmeains within follicles of secondary lympoid tissue underrgoing clonal expansion and producing the germinal center.

Question 25

What are 3 major events the B cells undergo in the germinal center?

Answer 25

affinity maturation
isotype switching
decision to become plasma cell or memory cell

Question 26

Somatic hypermutation.

Answer 26

during periods of intense proliferation in germinal centers; there are random mutations in the coding of the variable domain region

(these slightly altered idiotypes have increased affinity for antigen

Question 27

Affinity maturation.

Answer 27

when there are clones of B cells in germinal centers with more affinity for the antigen

Question 28

Avidity increases when?

Answer 28

When binding site of Ig increase