Week 2 Flashcards
(128 cards)
1
Q
Where are lymphoid nodules
A
in the cortex of lymph nodes
2
Q
Where are B cells located in a lymph node
A
germinal centers in lymphoid nodules
3
Q
Where are T cells located in lymph nodes
A
paracortex
4
Q
What is the flow of lymph thru a lymph node
A
- afferent lymphatic vessels
- subcapsular/marginal sinus
- trabecular/cortical sinus
- cortex and medullary cords
- medullary sinus
- efferent lymphatic vessels
5
Q
Tonsils are a type of
A
MALT
6
Q
What are the 3 types of tonsils
A
pharyngeal, palatine, lingual
7
Q
What structure do tonsils lack
A
afferent lymph vessels
8
Q
What layer of tonsils are the lymphatic nodules found
A
lamina propria
9
Q
What surrounds lymphatic nodules in tonsils
A
T cells
10
Q
How do tonsils prevent spread of infection to underlying tissues
A
a partial capsule of dense, fibrous CT
11
Q
What is a sequestered crypt
A
a crypt filled with debris and pus
12
Q
Structurally, how are the 3 types of tonsils different
A
palatine tonsils have many crypts, lingual tonsils have only 1 crypt, and pharyngeal tonsils have no crypts
13
Q
Where do palatine and lingual tonsils drain to
A
jugulodiagastric/tonsillar lymph nodes
14
Q
What type of epithelium do pharyngeal tonsils have
A
ciliated pseudostratified columnar epithelium which is RESPIRATORY epithelium
15
Q
Where do pharyngeal tonsils drain to
A
retropharyngeal lymph nodes
16
Q
Where are MALTs found
A
GI, respiratory, genital, and urinary tracts
17
Q
What is the main Ab formed in MALT
A
secretory IgA
18
Q
What are the 2 major MALT subdivisions
A
GALT (peyer’s, appendix, and tonsils)
BALT (bronchi)
19
Q
Where are GALTs found
A
wall of ileum
20
Q
What do the pharyngeal arches form from
A
mesoderm at 4-5 weeks
21
Q
What do the pharyngeal clefts form from
A
ectoderm
22
Q
What do the pharyngeal pouches form from
A
endoderm
23
Q
What embryological malformation results in Treacher Collins
A
1st and 2nd pharyngeal arch malformations
24
Q
What embryological malformation results in DiGeorge syndrome
A
3rd and 4th pharyngeal pouch malformations
25
5 Ab types in order of highest concentration to lowest
G A M E D
26
What Ab is a pentamer
IgM
27
What Ab can be dimer, monomer or trimer
IgA
28
What Ab is present in mucosa
IgA
29
What Ab is present in helminths and allergies
IgE
30
What Abs are present in naïve B cells
IgM and IgD
31
What is affinity maturation
prolonged or repeated exposure to an Ag results in the production of Abs with increasing affinity for the Ag
32
What is the most effective Ab response type
T-dependent
33
What is T-dependent humoral response
when follicular B cells recognize the protein Ag
34
What is T-independent humoral response
when marginal zone and B-1 B cells recognize polysaccharides, lipids and other non-protein Ags
35
Where are marginal zone B cells found
peripheral region of splenic white pulp
36
Where are B-1 B cells found
mucosal tissue and peritoneum
37
What type of Ab response produces high affinity Abs
T-dependent
38
What type of Abs are the most common produced by marginal zone B cells and B-1 B cells
IgM
39
What type of Abs are produced in primary Ab response
IgG and IgM
40
What type of Abs are produced in secondary Ab response
IgG (and IgA and IgE depending what type of pathogen)
41
What are the components of the BCR complex
BCR, Ig alpha, Ig beta
42
Memory cells express what type of Ab
IgG
43
How are memory cells long lived
because they only express IgG. Without IgD anymore, they cannot undergo anergy so they persist
44
What type of cells SECRETE IgM antibodies
plasma cells
45
What types of cells are found in the peripheral region of splenic white pulp
marginal zone B cells that participate in T-independent humoral immunity
46
What type of bacteria produce lipopolysaccharides
gram neg
47
What type of B cells respond to Ags in the mucosa and peritoneum
B-1s
48
How long does is take the immune system to mount a primary response
5-10 days
49
How long does it take the immune system to mount a secondary response
1-3 days
50
Where are macrophages located in lymph nodes
subcapsular sinus
51
First step of B cell activation involves 2 or more surface Igs clustering and binding the Ag at the same time. This is called
cross linking
52
What transduces the signal of Ag binding to surface Ig in B cell activation
proteins Ig alpha and Ig beta
53
When 2 or more surface Igs cross-link, the ____ of Ig alpha and Ig beta are _____
ITAMs are phosphorylated
54
What phosphorylates Ig alpha and Ig beta ITAMs
Fyn, Lyn, & Blk which are tyrosine kinases
55
Once the ITAMs are phosphorylated, they recruit
Syk tyrosine kinase
56
Sky tyrosine kinase phosphorylates
adaptor proteins
57
Phosphorylation of adaptor proteins in B cell activation ultimately leads to the production of enzymes which serve as
transcription factors to initiate proliferation and differentiation
58
What are the complement receptors expressed on the surface of B cells
CR2 or CD21
59
In T-independent B cell activation, what are the 2 signals required for activation
1. Ag recognition and thus cross-linking via BCR
2. (a) Complement recognition via CR2 or CD21
* ********OR********
(b) PAMP recognition via TLR
60
What are the transcription factors produced after Ag-mediated signal transduction in B cells
Myc, nFAT, NF-kB, AP-1
61
How does Ag-mediated activation of B cells prime them for interaction with T cells
Ag presentation and increased B7 expression
62
What are the 5 functional consequences of B cell activation by Ag
1. increased proliferation and survival
2. primed for interaction with T cell
3. increased responsiveness with cytokines
4. migration from follicle to T cell zone
5. Ab secretion
63
Where does the initial T-B cell interaction take place
T cell zone
64
4 basic steps of T-B cell interaction
1. Naïve T cells are activated to Ths in T cell zone via DCs presenting Ag via MHC II
2. Naïve B cells are activated in follicles via the same Ag
3. the activated B & T cells migrate toward each other and meet in the extrafollicular focus (site of initial Ab response)
4. some cells (B and Tfh cells) migrate back to follicle to form germinal centers for further Ab specialization
65
What type of Ag best activates T cells
protein Ag
66
What do adjuvants in vaccines do
stimulate the expression of costimulators on APCs
67
In order to migrate to B cells, activated T cells increase the expression of _____ and decrease the expression of _____. The opposite expression happens in B cells.
INCREASE CXCR5
DECREASE CCR7
****** opposite happens in B cell migration *******
68
In order for B cells that have been activated by Ag to be recognized by Th cells activated by the same Ag, they must
endocytose, process, and then display the Ag via MHC-II on the surface
69
In regards to a specific Ag, how do B and T cells differ in their recognition of it
B cells are capable of recognizing the native epitope (native=properly folded) where T cells recognize peptide fragments
70
What happens if T cells only receive the first activation signal
anergy
71
What are conjugate vaccines
when carrier proteins are added to weak Ags in order for B cells to elicit a T-dependent (aka much stronger) immune response versus relying on T-independent response.
****Used for Ags that T cells cannot recognize like bacterial polysaccharides hence the need for the carrier protein (which the T cell can recognize) *****
72
What are examples of common conjugate vaccines
PCV (pneumococcal) and Hib
73
What interaction stimulates isotype switching
CD40-CD40L
74
What are the 4 interactions between B & T cells
1. TCR binding MHC-II
2. CD40L binding CD40
3. CD28 binding B7
4. T cell cytokines binding B cell cytokine receptors
75
Upon initial B & T cell interaction, plasma cells are produced but
they are short-lived and produce few memory cells
76
Where does the majority of fully developed Ab responses take place
germinal centers
77
The T cells that travel to the germinal centers in fully Ab response are called
Tfh cells (follicular helper T cells)
78
The generation and function of Tfhs is dependent upon
ICOS
79
In order for Tfhs to migrate to follicles, they express high levels of
CXCR5
80
What cytokines are produced by Tfhs
IFN-gamma, IL-4, IL-17, IL-21
81
Mature, activated B cell proliferation form the
dark zone of the germinal center
82
Affinity selection takes place in the
light zones of the germinal center
83
What Abs work best for opsonization
IgG1 and IgG3
84
What Ab activates complement by the innate immune system
IgM
85
Cytokines produced in mucosal tissue responses that allow for IgA isotype switching
TGF-beta and BAFF
86
What B-T cell binding factor influences isotype switching
CD40L
87
If a B cell is only capable of producing IgM even after Th cell binding, what component would be lacking
CD40L----- as seen with X-linked hyper IgM syndrome in males
88
What enzymes allows for switch recombinaiton
AID-- activation induced deaminase
89
Isotype switching to IgG in humans is mediated by
IL-10
90
Isotype switching to IgE in humans is mediated by
IL-4
91
Affinity maturation ONLY occurs in what type of humoral response
T-dependent
92
How does AID work
it converts cytosines into uracils
93
Where does somatic HYPERmutation take place
in germinal centers
94
Where are follicular dendritic cells found
light zones of germinal centers
95
After undergoing somatic hypermutation, which B cells will be selected to survive
B cells whose Igs win the competition for binding to the Ag of FDCs or Tfhs ---- basically, FDCs and Tfh dangle the Ag and see who can bind it faster and better
96
What are plasmablasts
Ab-secreting B cells
97
Where do plasmablasts migrate to
bone marrow or mucosal tissues
98
Other than plasma cells, what else do high-affinity B cells become
memory B cells
99
Do memory B cells secrete Abs
no
100
What type of humoral immunity is the main one capable of producing long-lived memory B cells
T-dependent
101
Why can't non-protein Ags elicit a T-dependent response
MHC cannot recognize non-protein Ags which is required in order for T cells to recognize them
102
How does antibody feedback work
Circulating Abs form an Ab-Ag complex and then circulating B cells also recognize and bind the same Ag. The tails (Fc portion) of the bound Ab then bind back to the B cell via
Fc-gamma-RIIB receptor on the surface which sends inhibitory signals telling the B cell to shut off Ab production
103
Lupus is associated with polymorphisms of what receptor
Fc-gamma-RIIB
104
What is the purpose of antibody feedback
to turn off humoral responses once enough Ab has been produced and to also limit Ab responses to self-Ags
105
What protein associated with Fc-gamma-RIIB blocks ITAM on the BCR
ITIM---- TIM BLOCKS TAM
106
Where does complement bind on an Ab
Fc region
107
Where is the neonatal FcRn expressed
placenta, endothelium, and phagocytes
108
Why do IgGs have a longer half life
the FcRns prevent degradation and recycle IgG back into circulation
109
What would be the advantage to fusing protein drugs to the Fc region of IgGs
since IgGs have longer half lives thanks to FcRns, this allows the protein drugs to also have longer half lives
110
What 3 ways do Abs neutralize microbes and toxins
1. blocks penetration of microbe thru epi barrier
2. Ab blocks binding of microbe to infect cells
3. Ab blocks binding of toxin to cell receptor
111
What recognizes opsonin
Fc-gamma-RI on phagocytes
112
What is opsonization mainly used for
encapsulated bacteria (like pneumococci)
113
Why are pts who have had a splenectomy susceptible to encapsulated bacteria
the spleen is rich in phagocytes that phagocytose the opsonized encapsulated bacteria
114
What is ADCC
Ab-dependent cellular cytotoxicity--- when IgG1 and IgG3 attached to infected cells are recognized by
Fc-gamma-RIII on NK cells... which leads to the NK destroying the cell similar to CD8+ T cell
115
IgE recruits
eosinophils
116
What is the IgE receptor found on eosinophils
Fc-epsilon-RI
117
What cytokine promotes isotype switching to IgE
IL-4
118
What cytokine produced by Th2 cells activate eosinophils
IL-5
119
What are the 3 functions of the complement system
opsonization, inflammation, and cell lysis
120
The early step in all 3 complement pathways is to
generate as many C3 fragments as possible and bind them to microbe
121
A hypermetabolic state leads to
autoimmunity
122
A hypometabolic state leads to
cancer
123
What do T cells rely on for survival
glucose and fatty acid catabolism
124
What type of Ab would be found in peyer's patches
IgA
125
The tonsils, appendix, and Peyer's patches are aggregates of
MALT
126
What are the 2 functions of GALT
surveillance and facilitate immune response
127
What layer of the ileum are peyer's patches found
lamina propria
128
Where are T cells located in peyer's patches
in the zone between the lymphoid nodules
