5401 Exam 2 Study

what enzyme is Junctional Diversity mediated by and what does that enzyme do

TdT
adds random nucleotides to opened hairpin ends

what processes in the diversifying B cells antibodies do AID mediate

somatic hypermutation
class switching

what process in the diversifying of B cells antibodies does RAG1/2 Recombinase mediate

somatic recombination (aka V(D)J recombination)

what is immunogenicity

the ability of a substance to elicit an immune response in the body

which immunoglobulins are the first 2 classes expressed (naive B cells only express these)

IgM and IgD

which immunoglobulin isotype is secreted as a pentamer held together by J chain

IgM

what is the diff between affinity and avidity

Affinity = strength of binding between SINGLE antigen-binding site of an antibody and a SINGLE epitope of an antigen

Avidity= OVERALL strength of binding between multiple antigen-binding sites of an antibody and multiple epitope of antigen

what is the diff between monoclonal antibodies (mAbs) and polyclonal antibodies (pAbs)

mAbs are derived from a single B cell clone & recognize single, specific epitope
pAbs are produced by multiple B cell clones in response to same antigen & recognize multiple distinct epitopes

what region of a chimeric Ab is of murine origin

variable regions

what region of a humanized Ab is of murine origin

HV regions

what principle ensures that every B cell produces Ig of a single antigen specificity by allowing expression of only 1 heavy chain and 1 light chain per B cell

allelic exclusion

what region of an Ig allows flexibility for the Ig to bind 2 antigens on a pathogen surface

hinge region

what stage of B cell development does heavy chain rearrangement occur

Pro-B Cell

what is anergy defined as

functional inactivation of a cell

if an immature B cell fails to interact with self-antigen, what are the 3 possible outcomes

receptor editing (if cross linking occurs)
anergy (no cross linking)
apoptosis

during B cell development, stromal cells secrete ________ to attract immature B cells to _____
a) CCL19; HEV
b) CCL21; HEV
c) CXCL8; lymph node
d) CXCL13; primary lymphoid follicle

b) CCL21; HEV

during B cell development, DCs secrete ______ and ________ to attract B cells into __________
a) CCL19; CCL21; lymph node
b) CCL21; CCL12; HEV
c) CXCL13; CCL19; primary lymphoid follicle
d) CXCL21; CXCL8; primary lymphoid follicle

a) CCL19; CCL21; lymph node

during B cell development, FDCs secrete ______ to attract B cells into ________
a) CCL19; lymph node
b) CCL21; HEV
c) CXCL13; primary lymphoid follicle
d) CXCL8; primary lymphoid follicle

c) CXCL13; primary lymphoid follicle

Pre-B cells have how many opportunities to produce a productive light chain rearrangement during B cell development

4 opportunities (2 𝜅 and 2 𝝀 loci)

if immature B cells fail to interact with FDCs in the primary lymphoid follicle of the lymph node, it will...
a) enter a state of anergy
b) become a naive B cell
c) die by neglect
d) undergo receptor editing

c) die by neglect

after a TCR is made, it will NOT move from the ER to the cell surface unless it associates with...

CD3 and 𝜁 chain via charge-charge interactions

T or F? MHC II is present on all cells while MHC I is usually only on antigen presenting cells

false
MHC I is on all cells while MHC II is on antigen presenting cells (i.e. DCs, macrophages)

MHC I presents peptides from [intracellular/extracellular] antigens while MHC II presents peptides from [intracellular/extracellular] antigens

MHC I - intracellular
MHC II - extracellular

intracellular antigen is processed by a proteasome into peptides. the peptides are transported into ______ by ______

the ER
TAP

what releases CLIP from MHC II once a "good-fitting" antigen is found

HLA-DM

what is HLA

the way human MHC are named

a T-cell progenitor can go through 2 rearrangement competitions. the first is between ______ while the 2nd is between ______
a) ɣ:ẟ and β ɣ:ẟ and ɑ
b) ɣ:ẟ and ɑ ɣ:ẟ and β
c) ɑ and β ɣ:ẟ and β
d) ɑ and β ɣ:ẟ and ɑ

a) ɣ:ẟ and β ɣ:ẟ and ɑ

what is the diff between positive and negative selection during T cell development

positive selection: tests that TCR CAN bind MHC
negative selection: tests that TCR can NOT bind self-antigen

what is the transcription factor that allows thymic epithelium cell to express genes from other cells and protects from autoimmunity against periphery

AIRE

what induces the upregulation of B7 on DCs

PAMPs

what are the 2 ways naive T cells can enter lymph nodes

1. via lymphatic vessels
2. those circulating in blood can enter via HEV

what are ITAMs and what do they do

ITAMs are protein motifs that, when phosphorylated, can bind to ZAP 70 and initiate the signaling cascade for T cell activation and proliferation

once activated, T cells secrete ____ to cause proliferation

IL-2

which of the following Th cells is incorrectly matched with the cytokines they secrete:
a) Th1 - IFN-ɣ
b) Th2 - IL-4
c) Th3 - IL-15
d) Treg - TGF-β

c) Th3 - IL-15
correct is Th3 secretes IL-17

what are 2 ways antigen for MHC I can be received (select the 2)
a) receptor mediated endocytosis
b) macropinocytosis
c) infection of DC
d) cross-presentation in DC

c) infection of DC
d) cross-presentation in DC

if TCR binds to MHC:antigen but there is no co-stimulation, what happens to the T-cell

it enters anergy

which of the following Th is CORRECTLY matched with the type of immunity they mediate:
a) Th1 --> macrophage based immunity
b) Th2 --> antibody based immunity
c) Th17 --> cell based immunity
d) Treg --> inflammation based immunity

b) Th2 --> antibody based immunity

correct pairings:
Th1 cell based
Th2 antibody based
Th17 inflammation based
Treg suppressor

which of the following effector T cells make cytokines that positively feedback (select all that apply)
a) Th1
b) Th2
c) Th3
d) Treg

a) Th1
b) Th2
d) Treg

what are the 2 ways cytotoxic (CD8) T cells are controlled (to prevent unregulated killing)

1. a lot of B7 have to be expressed for CD8 T cells to be activated
2. need IL-2 from helper T cells after up-regulation of IL-2R