Specific Acquired Immunity

Question 1

What pathway is taken to display antigens on MHC Class I?

Answer 1

• Antigens are synthesized with in the cell

- Cell antigens of antigens from cell infections

Question 2

What cell types express MHC Class I?

Answer 2

Expressed on all cells except RBCs. Lack of expression on RBCs may play a role in persistence of the malaria parasite, plasmodium

Question 3

What T cell types interact with MHC Class I?

Answer 3

Recognized by CD8+ killer T cells

Question 4

What is the result of T cell interaction with MHC Class I?

Answer 4

It surveys every cell in the body and makes sure it’s doing what it should be doing,
If CD8+ cell is activated:
-CD8+ cells expand/clone
-Daughter cell binds cell showing activation peptide
-T cell delivers lethal hit to that cell by signaling the target cell to commit suicide through apoptosis
-Target cell’s nucleus disintegrates and the cell dies

Question 5

What pathway is taken to display antigens on MHC Class II?

Answer 5

Antigens are products of uptake from the environment and phagocytosis.

Question 6

What cell types express MHC Class II?

Answer 6

Expressed on monocytes/macrophages, dendritic cells, B cells and epithelial cells of the thymus.

Question 7

What T cell types interact with MHC Class II?

Answer 7

Recognized by CD4+ helper T cells.

Question 8

What is the result of T cell interaction with MHC Class II?

Answer 8

Antibodies will be produced? B cell response?

Question 9

What is is MHC known as?

Answer 9

HLA (human leukocyte antigens) - inherited in mendelian fashion - some from each parent

Question 10

What are the common lymphocyte markers?

Answer 10

Antigen receptors & CDs

Question 11

Which lymphocytes markers are expressed on T cells?

Answer 11

• TCR (alpha-beta or gamma-delta) - antigen receptor
• CD3 (part of TCR complex)
• Some have CD4, some have CD8, some have CD23

Question 12

Which lymphocyte markers are expressed on B cells?

Answer 12

Immunoglobulin (Ig) - antigen receptor

• CD1
• CD19
• CD20
• CD23
• CD40
• CD79a (part of BCR complex)
• CD79b (part of BCR complex)

Question 13

What are the five specialized subtypes of T helper cells?

Answer 13

Th1, Th2, Th17, Tfh, Treg (not helper: CTL)

Question 14

What main cytokines drive a HSC to a lymphoid progenitor cell?

Answer 14

IL-7 and IL-3

Question 15

What cytokines are general activators of T cells?

Answer 15

IL-2 and IL-15

Question 16

What cytokines drive T helper cells to Th1 helper cells?

Answer 16

IL-12 and IFN-gamma

Question 17

What cytokines drive T helper cells to Th2 helper cells?

Answer 17

IL-4

Question 18

What cytokine down regulates Th1?

Answer 18

IL-10

Question 19

What cytokines down-regulates both Th1 and Th2?

Answer 19

TGF-beta

Question 20

Are T helper cells considered CD4+ or CD8+ T cells?

Answer 20

CD4+ T cells

-CD4+ increases their affinity for antigen and helps them get activated.

Question 21

What do Th1 (helper) cells do?

Answer 21

• Recognize antigen and make a lymphokine that attracts thousands of macrophages (heavy duty phagocytes) to area where antigen has been recognized.
• This intense inflammation can wipe out a serious infection (or a transplanted kidney)

Question 22

What do Th2 (helper) cells do?

Answer 22

• Stimulated macrophages to become ‘alternatively activated’, able to function in walling-off pathogens and promoting healing, a process that usually takes place after the pathogen-killing Th1 response.
• They are very important in parasite immunity

Question 23

What do Th17 cells do?

Answer 23

• Similar to Th1 in that their main role is to cause focused inflammation
• More powerful than Th1
• Have been implicated in many serious forms of autoimmunity

Question 24

What do Tfh (follicular helper) cells do?

Answer 24

• Stimulated by antigen and migrate from T cell areas of lymph nodes into the B cell follicles
• In B cell follicles, they help B cells get activated and make IgM, IgG, IgE and IgA antibody subclasses.

Question 25

What do Treg (regulatory) cells do?

Answer 25

- Make cytokines that suppress the activation and function of Th1, Th17 and Th2 cells - They keep the immune response in check

Question 26

What do CTL (cytotoxic/killer T cells) do?

Answer 26

-Destroy any body cell they identify as bearing a foreign or abnormal antigen on its surface

Question 27

How are target cells recognized for CTL cells?

Answer 27

- They examine surfaces of incoming dendritic cells for presented antigen fragments. - In this case, they are looking for fragments on a different class of antigen-presenting molecule, called MHC Class I, which is not only on dendritic cells, but on ALL cells except RBCs

Question 28

What is the general mode of action that killer T cells use to kill target cells?

Answer 28

1. If activated, a clone of the CD8+ T cells gets expanded and the daughters circulate in large numbers throughout the body 2. When one of the daughters of a stimulated CD8+ T cell binds a cell showing its "activation" peptide, the T cell delivers a lethal hit to that cell by signaling the target cell to commit suicide through apoptosis. 3. The target cell's nucleus disintegrates and the cell dies. 4. The activated killer T cells then is free to find more targets. This is a great way to eliminate infected cells.

Question 29

What are five common B cell disorders?

Answer 29

1. X-linked agammaglobulinemia 2. CD40 ligand deficiency 3. Activation-Induced Cytidine Deaminase Deficiency 4. Common variable immunodeficiency 5. Omenn Syndrome

Question 30

What are the five common T cels disorders?

Answer 30

1. X-linked severe combined immunodeficiency 2. Omenn syndrome 3. DiGeorge syndrome 4. Hemophagocytic lymphohistiocytosis 5. IPEX

Question 31

What causes X-linked agammagglobulinemia?

Answer 31

An absence of B lymphocytes

Question 32

What causes CD40 ligand deficiency?

Answer 32

Failure of immunoglobulin class switching

Question 33

What causes activation-induced cytidine deaminase deficiency?

Answer 33

-Failure of immunoglobulin class switching

Question 34

What causes common variable immunodeficiency?

Answer 34

A failure to produce antibodies against particular antigens

Question 35

What causes Omenn syndrome?

Answer 35

- VDJ recombination failure. | - Cannot produce BCRs or TCRs

Question 36

What causes X-linked severe combined immunodeficiency?

Answer 36

A failure to produce mature T lymphocytes

Question 37

What causes DiGeorge Syndrome?

Answer 37

Failure of the thymus to develop correctly

Question 38

What causes hemophagocytic lymphohistiocytosis?

Answer 38

Failure of CD8+ T cells and NK cells to produce and/or release lytic granules

Question 39

What causes IPEX?

Answer 39

A failure of peripheral tolerance due to defective regulatory T cells