Diebel Test 4

Question 1

Anergy

Answer 1

Naive T cells always present CD28. APC’s must also present CD80/86 (only macrophages that don’t constituitively present 80/86).

If APC’s don’t also present 80/86 = anergy and T cells die.

Failsafe mechanism to ensure T cells are only appropriately active.

Question 2

CTLA-4

Answer 2

Even stronger binder to 80/86 that is produced after a burst of IL-2 to prevent runaway T cell response.

When CTLA-4 binds 80/86 = activation inhibition

Question 3

TAP 1 and 2

Answer 3

Transporter associated w/ Antigen Processing

Complex that extends across the RER membrane and facilitates the passage of cytosolic pathway peptides to the lumen of the RER where loading of the peptides to Class I molecules can take place.

Found at same locus as HLA.

Question 4

Calnexin

Answer 4

Protein that holds the alpha chain and waits for beta piece to join.

Question 5

ERAAP

Answer 5

Trims excess protein. Then MHC I is mature and can move through golgi to cell membrane.

Question 6

DRiPs

Answer 6

Defective Ribosomal Products

Proteins synthesized incorrectly that are rapidly degraded and presented on the cell surface via MHC I molecules.

Allows the recognition and killing of cells that have aberrant DNA and thus produce aberrant proteins.

Question 7

Fas

Answer 7

The death receptor that when bound by CTL or NK cells results in apoptosis.

Question 8

Granulysin

Answer 8

Protein released by CTL or NK cells that activates apoptosis by cleavage of capsases.

Question 9

Perforin

Answer 9

Released by CTLs or NKs when Fas ligand is bound triggering apoptosis.

Form a pore on target cell membranes.

Question 10

Invariant chain

Answer 10

=CD74

Assists in the folding of class II alpha and beta chains, binds to the peptide-presenting site of the class II molecules, and assists in the transport of the MHC II molecules from golgi to cytoplasmic vesicles.

Question 11

CLIP

Answer 11

CLass-II associated Invariant chain Peptide.

Proteolytic cleavage gradually digest the invariant chain leaving the short CLIP fragment bound to the antigen presenting site on the MHC II.

Question 12

CD45R

Answer 12

Receptor for cell growth and differentiation that remains expressed on the surface as intermediate pro-B cells and remains expressed throughout the remainder of B-cell ontogeny.

Question 13

c-Kit

Answer 13

Binds to stem-cell factor expressed on bone marrow stromal cells. This induces the pro-B cells to proliferate and differentiate into pre-B cells

Question 14

IL-7

Answer 14

Promotes B-cell lineage development.

Question 15

Blys

Answer 15

B-lymphocyte stimulator

Signaling through its receptor BR3 is important for the survival of pre-immune B-cell stages from transition stage onwards.

Question 16

IL-4, IL-3, and low-molecular-weight B cell growth factor (L-BCGF)

Answer 16

Important signaling molecules for initiatiing the process of B-cell differentiation.

Question 17

BTK

Answer 17

Gene encoding the enzyme Bruton’s Tyrosine Kinase.

Key enzyme involved in signal transduction downstream of the pre-BCD and BCr.

Mutated in immunodeficiency XLA. –> very few circulating B cells and negligible serum Ig.

85% of agammaglobulinemia (AKA Bruton’s Agammaglobulinemia)

Question 18

T-Independent Antigens (TI)

Answer 18

Antigens that can activate B cells without MHC class II restricted T cell help.

Can be divided into two groups (TI-1 and TI-2) based on the manner in which they activate B cells.

Activate B1 B cells (IgM only)

Poor memory

Question 19

TI-1

Answer 19

Predominately bacterial cell wall components. Prototype = LPS.

Question 20

TI-2

Answer 20

TI-2 antigens are predominately large polysaccharide molecules w/ repeating antigenic determinants.

Question 21

Superantigen

Answer 21

Complexes bind TCR and MHC regardless of costimulatory molecules causing extreme levels of T cell activation which is toxic.

Question 22

CD25

Answer 22

High affinity receptor for IL-2 found on the surface of mature CTL’s.

IL-12 (produced by APC after TH1 production of IFN-y) causes switch to CD25 active receptor form naive CD8.

Question 23

L-selectin and CCR7

Answer 23

Cause homing and retiention in lymph nodes.

Expressed high levels in Naive CTL-P

Low levels in Effector CTL

Question 24

LFA-1

Answer 24

On CTL and binds to ICAMS on target cell.

Antigen activation converts LFA-1 from low affinity state to high affinity state for better binding.

Returns to low affinity state after 5-10 minutes resulting in CTL disassociation from target cell.

Question 25

CD56low NK cells

Answer 25

90% of NK cells.

Effective killers of target cells.

Question 26

CD56high NK cells

Answer 26

Release cytokines (IFN-y). Tilts immune response towards TH1’s and M1’s. Don’t have granules

10% of NK cells.

Question 27

CD16

Answer 27

Expressed by NK cells. (also NKRs).

Recognized IgG bound to cells.

Question 28

NKG2

Answer 28

Lectin like receptors

Bind to HLA-E and MHC I.

Most are activating

All are heterodimers except NKG2B

NKG2A is inhibitory and trumps all others.

NKG2E is main activating signal.

Question 29

KIR

Answer 29

=killer cell immunoglobulin-like receptors

Bind to most MHC class I molecules (HLA-A, HLA-B, and HLA-C)

Most receptors are inhibitory.

Question 30

Antibody Dependent Cell-mediated Cytotoxicity (ADCC)

Answer 30

Effector cells: NK cells, mphages, monocytes, nphils, ephils

Effector cells bind the antigent via Fc receptor

Killing is mediated by:

• cytolytic enzyme release by mphages, nphils, and ephils
• TNF release by NK cells, monocytes, mphages
• perforin release by NK and ephils
• granzyme release by NK