[DISCUSSION] MODULE 3 Flashcards
1
Q
• Developmental history of
the immune system
during evolution
A
PHYLOGENY
2
Q
• Development of the
immune system as a
comparative relation of
man and other animals
A
PHYLOGENY
3
Q
→ most developed
and most complex
immune system
A
MAN
4
Q
Man: most developed & most
complex immune system
EVIDENCES:
A
- Demonstrable hallmarks
- Well-developed immune system organs
- Cells are highly specialized
- Well developed complement system
- Separate function of humoral and cellular
immunity - Ability to reject graft and mount the
response is reasonably developed at birth
5
Q
• Developmental history of
the immune system
within a species
A
ONTOGENY OF THE IMMUNE SYSTEM
6
Q
FUNCTIONS OF LYMPHOID TISSUES
A
- To provide an environment for the
maturation of the immune system’s
immature cells
2.To concentrate lymphocytes into organs
that drain areas of antigen insult
3.To permit the interaction of different
classes of lymphocytes
4.To provide an efficient vehicle for the
disbursement of antibodies and other
soluble factors from lymphocytes and
other immune cells.
7
Q
– A tissue in which lymphocytes are found
A
LYMPHOID TISSUE
8
Q
– Diffuse arrangements of individual cells to encapsulated organs
A
LYMPHOID TISSUE
9
Q
– Organized cylindrical clusters of lymphocytes
A
LYMPHOID FOLLICLES
10
Q
Organized cylindrical clusters of lymphocytes that, when gathered into groups, are called
A
lymphoid patches
11
Q
– Usually groups of follicles that are surrounded or encapsulated by specialized supporting tissues and membranes
A
LYMPHOID ORGANS
12
Q
Lymphocytes develop central tolerance is establised
A
Primary Lymphoid Tissues
13
Q
All lymphocytes arise from HSCs in the bone marrow and B cells mature in this site
A
Primary Lymphoid Tissues
14
Q
T cells migrate from the bone marrow to the thymus and mature in this site
A
-Bone marrow
-Thymus
15
Q
Thymus
T
lymphocytes
(%)
B lymphocytes
(%)
A
100
0
16
Q
Blood
T
lymphocytes
(%)
B lymphocytes
(%)
A
80
20
17
Q
Lymp nodes
T
lymphocytes
(%)
B lymphocytes
(%)
A
60
40
18
Q
Spleen
T
lymphocytes
(%)
B lymphocytes
(%)
A
45
55
19
Q
Bone marrow
T
lymphocytes
(%)
B lymphocytes
(%)
A
20
90
20
Q
• the primary site of
hematopoiesis in the
adult human.
A
BONE MARROW
21
Q
BONE MARROW
– about (?)% myeloid
lineage cells
A
60–70
22
Q
BONE MARROW
– (?)% erythroid lineage
cells
A
20–30
23
Q
BONE MARROW
– (?)% lymphoid lineage cell
A
10
24
Q
BONE MARROW
– remainder consisting of
(1) plus
various other (?)
such as stromal cells and
adipocytes
A
- mast lineage cells
- non-hematopoietic cell types
25
• Where immature T cells
complete their development.
THYMUS
26
• Sites for antigen-driven immune cells
SECONDARY LYMPHOID TISSUES/ORGANS
27
• Antigen-dependent lymphocyte
differentiation occurs
SECONDARY LYMPHOID TISSUES/ORGANS
28
• Major site for the interaction of lymphocytes with antigen during a primary adaptive response
Lymph nodes
29
• Occur along the entire length of lymphatic system
but are clustered in a few key regions
Lymph nodes
30
• Bean-shaped, encapsulated structures 2- 10 mm in diameter
Lymph nodes
31
• Contain large numbers of lymphocytes, FDCs and
APCs
Lymph nodes
32
– Contains large numbers of resting B cells,
FDCs and macrophages arranged in lymphoid
follicles
Cortex
33
– Home to many T cells and thymic DCs
Paracortex
34
• Antibody-secreting plasma cells
Medulla
35
• Most antigens escaping
the innate immune response, (?) make their way into the tissues, are collected in the lymphatic system and are channeled into local lymph nodes.
MALT and
SALT
36
• Most antigens escaping
the innate immune response, MALT and
SALT make their way into the tissues, are collected in the (?) and are channeled into local lymph nodes.
lymphatic system
37
• Most antigens escaping
the innate immune response, MALT and
SALT make their way into the tissues, are collected in the lymphatic system and are channeled into (?).
local lymph nodes
38
SEVERAL WAYS BY WHICH AN
ANTIGEN CAN ACCESS THE
BLOOD CIRCULATION:
1. Directly into the blood (e.g.,
drug injection, insect/snake
bites).
2. Overwhelming local infection
can result in penetration of
underlying blood vessels by
the pathogen.
3. Systemic infection contained
by the lymph nodes pours into
the efferent lymph, and
eventually dumped into the
blood.
39
• Abdominal organ that traps blood-borne
antigens
Spleen
40
• Entire blood volume of the adult courses
through the spleen 4x daily
Spleen
41
• Each arteriole in the spleen is encased by a
PERIARTERIOLAR LYMPHOID SHEATH (PALS)
Spleen
42
– Cylindrical arrangement of tissue
PERIARTERIOLAR LYMPHOID SHEATH (PALS)
43
– Populated mainly by mature T cells
PERIARTERIOLAR LYMPHOID SHEATH (PALS)
44
– Containing low numbers of plasma cells,
macrophages and conventional DCs
PERIARTERIOLAR LYMPHOID SHEATH (PALS)
45
Spleen
• Tissue surrounding the PALS contains:
– Lymphoid follicles
– Surrounding the follicles is the:
– MARGINAL ZONE
46
• Resting B cells and macrophages
Lymphoid follicles
47
• Contains particular B cell subsets
MARGINAL ZONE
48
– Contain splenic arterioles with their PALS, the follicles and the marginal zone
WHITE PULP
49
– Abundant erythrocytes
RED PULP
50
– Consists of splenic cords and venous sinuses and surrounds the white pulp
RED PULP
51
FUNCTION OF THE RED PULP:
– Filtering of particulate material from the blood
– Disposal of senescent or defective erythrocytes
and leukocytes
52
MALT (Mucosa-associated lymphoid
tissues)
– NALT (Nasopharynx-associated lymphoid tissue)
– BALT (Bronchi-associated lymphoid tissue)
– GALT ( Gut-associated lymphoid tissue)
53
• Tonsils
NALT (Nasopharynx-associated lymphoid tissue)
54
• Peyer’s patches
• Appendix
GALT ( Gut-associated lymphoid tissue)
55
LYMPHOID TISSUE ORGANIZATION
-Diffuse lymphocytes
-Follicle
-Patch
-Organ
56
Primary and Secondary Lymphoid
Tissues
-BALT
-NALT
-GALT
-SALT
-Thymus
-Bone marrow
-Lymp node
57
LYMPH NODE
-Afferent lymphatic vessels
-Cortex
-Paracortex
-Medulla
-Lymphoid follicle
-Capsule
-Subcapsular sinus
-Efferent lymphatic vessel
58
SPLEEEEEEEEEENNNNN!!!
-Lymphoid follicles
-Arteriole
-Marginal zone
-PALS
-Capsule
-Trabeculae
-Hilus
-Efferent lymphatic vessel
59
Components of NALT and BALT
-Ciliated epithlial cell
-Mucus
-Commensal organisms
-Nose hairs
-Lingual tonsil
-Palatine tonsil
-Goblet cell
-M cell
-Trachea
-lambda gamma T cell
-Esophagus
-Submucosal gland
-Bronchus
-Pharyngeal tonsil
-Plasma cell
-alpha beta T cell
-Macrophage
-Interfollicular region
-Follicle
-Immature DC
60
• With the SALT, protect the body at all surfaces that interfere with the external environment
MALT (Mucosa-associated lymphoid
tissues)
61
• Populations of mature T & B lymphocytes, DCs, NK and macrophages
MALT (Mucosa-associated lymphoid
tissues)
62
• Comprises small populations of leukocytes in
the epidermis and dermis
SALT (Skin-associated lymphoid tissues)
63
• EPIDERMIS → (?)
Langerhans cells
64
• DERMIS →(?)
T cells, dermal DCs, macrophages
65
– Entire network of vessels and ducts that
collects and channels the lymph and its
contents throughout the body
Lymphatic system
66
– Connected to the blood circulation
Lymphatic system
67
• (?) empties the lymph into the right subclavian vein
Right lymphatic duct
68
• (?) connects with the left subclavian
vein
Thoracic duct
69
LYMPHATIC SYSTEM
-Right lymphatic duct
-Right subclavian vein
-Lymphatic vessels of mammary gland
-Cistema chyli
-Lymphatic vessels of lower limb
-Cervical lymph nodes
-Thoracic duct (left lymphatic duct)
-Lymphatic vessels of upper limb
-Left subclavian vein
-Axiliary lymph nodes
-Intestinal and mesenteric lymph nodes
-Abdominal lymph nodes
-Inguinal lymph nodes
-Popliteal lymph nodes
70
• function in cell-mediated immunity
T CELLS
71
T CELLS
• function in cell-mediated immunity:
– delayed hypersensitivity
– graft rejection
– graft-versus-host reactions
– defense against intracellular organisms (such as
tubercle bacillus and Brucella)
– defense against neoplasms
72
• majority of circulating lymphocytes are (?) that have a life span of months to years
T cells
73
• Perform in humoral immunity
B CELLS (and their progeny)
74
• minor population (10%–20% of the
lymphocytes)
B CELLS (and their progeny)
75
• probably have a short life span measured in days (with the exception of memory B cells)
B CELLS (and their progeny)
76
• distinguished by the presence of
considerable Ig on their surface membranes
B CELLS (and their progeny)
77
• Markers to differentiate T cells and B cells
SURFACE MARKERS ON
LYMPHOCYTES
78
• Distinguish the developmental stages of the 2 types of cells
SURFACE MARKERS ON
LYMPHOCYTES
79
• Detected by monoclonal antibodies
SURFACE MARKERS ON
LYMPHOCYTES
80
• CLUSTER OF DIFFERENTIATION
– Numerical designation
– Reference in standardizing names of membrane
proteins found on all wbcs
– Currently numbers more than 350
– Human Cell Differentiation Molecules (Dec.
2004)
81
B CELL DEVELOPMENT
TWO PHASES:
1. Maturation phase
2. Differentiation phase
82
– Hematopoietic stem cell (HSC) divides and eventually generates mature naïve B cells
Maturation phase
83
– Antigen independent
Maturation phase
84
– Begins in the bone marrow
Maturation phase
85
– Ends with mature naïve B cells taking up
residency in the secondary lymphoid tissues
Maturation phase
86
(?) divides and
eventually generates mature naïve B cells
Hematopoietic stem cell (HSC)
87
Maturation phase
– MAJOR DEVELOPMENTAL STAGES:
• HSC → MPP → CLP → Pro-B cell → Pre-B cell →
Immature naïve B cell → Transitional B cell →
Mature naïve B cell
/MFECh
88
Differentiation phase
Two stages:
a. Activation of a mature B cell by its
specific antigen
b. Generation of antigen-specific plasma cells and memory B cells
89
(?) → recognized by the presence of a surface molecule called CD45R
Earliest B cell precursor
90
(?) → first hematopoietic cells clearly recognizable as being of the B cell lineage
Early pro-B cells
91
• Identified by their expression of certain B lineage markers and their Ig genes are still in the germline configuration
PRO-B CELLS (Progenitor B cells)
92
(?) have yet to undergo V(D)J
recombination
Igh, Igk, Igl loci
93
• Transcription factors, or growth factors necessary to differentiate common lymphoid precursors into pro-B cells
PRO-B CELLS (Progenitor B cells)
94
– E2A, EBF (early B-cell factor), paired box protein 5 (PAX)
PRO-B CELLS (Progenitor B cells)
95
– IL-7 → most important; regulates
proliferation and differentiation of B cell precursors
PRO-B CELLS (Progenitor B cells)
96
– All are produced in the bone marrow
PRO-B CELLS (Progenitor B cells)
97
(?) → most important; regulates
proliferation and differentiation of B cell precursors
IL-7
98
PRO-B CELLS (Progenitor B cells)
• Distinctive markers:
– CD19, CD45R, CD43, CD24, c-Kit
99
– (?) → interacts with a cell surface molecule called stem cell factor
c-Kit
100
– (?) →coreceptor that helps to regulate further B cell development & activation
CD 19
101
– (?) → membrane gp found on all HP cells but the type found on B cells is the largest form →designated CD45R
CD45
102
– (?) → tyrosine-specific phosphatase involved in signaling in B cell activation
CD45R
103
– (?) → remain on cell surface throughout subsequent developmental stages
CD 19, CD24, & CD43
104
PRO-B CELLS (Progenitor B cells)
• Intracellular proteins found:
– TdT (terminal deoxyribonucleotidyl
transferase)
– RAG-1 & RAG-2 (recombination-activating genes) enzymes
105
• When synthesis of the heavy chain part of the Ab molecule occurs, this stage begins
PRE-B CELLS (Precursor B cells)
106
• First heavy chains synthesized:
u chains
107
• Lose the CD43 marker, c-Kit and TdT
PRE-B CELLS (Precursor B cells
108
• Express u chains on the cell surface
PRE-B CELLS (Precursor B cells
109
• Accompanied by an unusual light chain molecule called a (?)
surrogate light chain
110
– consist of 2 short polypeptide chains noncovalently associated with each other
surrogate light chain
111
– Not Ig proteins, but essential in regulating B-cell development
surrogate light chain
112
(?) → consist of 2 heavy chains with the surrogate light chains + 2 very short chains, Ig-a/Ig-b
Pre-B cell receptor
113
– Adheres to bm stromal cell membranes
Pre-B cell receptor
114
– Transmits signal to prevent rearrangement of any other heavy-chain genes
Pre-B cell receptor
115
(?) survive and proceed to further differentiation
Only pre-B cells expressing the m heavy chains with the SLC
116
• Distinguished by the appearance of complete IgM molecules on the cell surface
IMMATURE B CELLS
117
• Rearrangement of the genetic sequence coding for light chains on either chromosome 2 or 22 has taken place by this time
IMMATURE B CELLS
118
• Completion of rearrangement commits a cell to produce an antibody molecule with specificity for a particular antigen or group of related antigens
IMMATURE B CELLS
119
• Variable regions, which occur on both the L & H chains, determine its specificity
IMMATURE B CELLS
120
(?), which occur on both the L & H chains, determine its specificity
Variable regions
121
• Once surface immunoglobulins appear, u chains are no longer detectable in the
cytoplasm
IMMATURE B CELLS
122
• Other surface proteins:
- CD21
- CD40 & MHC Class II molecules
123
– (?) → receptor for C3d
CD21
124
– (?) → important for interaction of B cells with T cells
CD40 & MHC Class II molecules
125
• (?) give a negative signal to
immature B cells, resulting in arrested
maturation and cell death
Self- antigens
126
(?) are deleted from the bone marrow by the process of programmed cell death or apoptosis
Many B cells capable of producing antibody to self-antigens
127
Many B cells capable of producing antibody to self-antigens are deleted from the bone marrow by the process of programmed cell death or (?)
apoptosis
128
(?) receives an intracellular signal to halt development
Autoreactive B cells
129
The cell is given a brief period to try to further rearrange its Ig loci and stave off apoptosis by altering its antigenic specificity. This secondary gene rearrangement is called (?)
RECEPTOR EDITING
130
• Occurs primarily in the L chain
Receptor Editing
131
– B cell dies by apoptosis & is said to be
negatively selected
• If receptor editing fails
132
– The BCR no longer recognizes self antigen
• If receptor editing is successful
133
– Cell appears to receive a positive selection signal that sustains survival
• If receptor editing is successful
134
Cell of Bone Marrow
-Hematopoietic stem cell
-Lymphoid cell
-Pro-B cell
-Pre-B cell
-Immature B cell
-Mature B cell
135
Cell of Peripheral pymphoid organs
-Mature B cell
-Activated B cell
-Memory B cells of various isotypes
-IgG
-IgA
-IgE
136
• Remain in the bm for 1-3 days before commencing the expression of new
adhesion molecules and homing
receptors that allow them to leave the bm and travel in the blood to the
secondary lymphoid tissues
IMMATURE B CELLS
137
• Extravasate from the blood first into the red pulp of the spleen and then into its PALS
TRANSITIONAL TYPE 1 B CELLS (T1 B cells)
138
• After 24 h in the PALS, T1 B cells in the
PALS become (?), or T2 B cells
transitional type 2 B cells
139
• A cytokine called (?)
BAFF (B lymphocyte activating factor belonging to the TNF
family)
140
– essential for transition and T2 B cell survival
BAFF (B lymphocyte activating factor belonging to the TNF
family)
141
• Start to colonize the B cell rich areas of the spleen and acquire the ability to emigrate to other secondary lymphoid
tissues, particularly the lymph nodes
TRANSITIONAL TYPE 2 B CELLS (T2 B
cells)
142
• Also commence the surface expression of IgD as well as IgM
TRANSITIONAL TYPE 2 B CELLS (T2 B
cells)
143
• Once established in the lymphoid follicles, they become mature B cells in the periphery
MATURE NAÏVE B CELLS IN THE PERIPHERY
144
• Also known as follicular B cells
MATURE NAÏVE B CELLS IN THE PERIPHERY
145
• Slightly lower levels of mIgM than T2 B cells but higher levels of mIgD
MATURE NAÏVE B CELLS IN THE PERIPHERY
146
• Permanently lose expression of the RAG-1 & RAG-2
MATURE NAÏVE B CELLS IN THE PERIPHERY
147
• Now poised to encounter antigen
MATURE NAÏVE B CELLS IN THE PERIPHERY
148
(?)→ produces 109
mature naïve B cells every day
Adult human bone marrow
149
Chances of B cells being stimulated by
specific antigen are extremely limited: only
(?) encounters
specific antigen and prevents death by
apoptosis
1 in 105 peripheral B cells
150
THREE MAJOR CLASSES OF B CELL IMMUNOGENS:
1. T-INDEPENDENT-1 (Ti-1) ANTIGENS
2. T-INDEPENDENT-2 (Ti-2) ANTIGENS
3. T-DEPENDENT ( Td) ANTIGENS
151
• Both types of (?) can activate B cells to produce antibodies without interacting directly with T cells
Ti antigens
152
(?) bind to the BCRs to initiate activation but cannot induce plasma cell differentiation and antibody production unless
the B cell interacts directly with a Th effector
cell activated by the same antigen
Td antigens
153
T cell help takes the form of:
– Cytokines
– Intercellular contacts mediated by
costimulatory molecules
154
• Proteins on the surfaces of lymphocytes whose engagement by specific ligand is necessary for complete activation
costimulatory molecules
155
• T cell help allows activated B cells to
undergo:
– Somatic hypermutation
– Isotype switching
– Memory B cell production
156
Requires direct interaction
with a T cell for B cell
activation
Td ANTIGEN
157
Requires T cell cytokines
Td ANTIGEN
Ti-2
ANTIGEN
158
Epitope structure Td ANTIGEN
Unique
159
Epitope structure Ti-1 ANTIGEN
Mitogen
160
Epitope structure Ti-2
ANTIGEN
Repetitive
161
Protein
Yes
Td ANTIGEN
162
Protein
Could be
Ti-1 ANTIGEN
Ti-2
ANTIGEN
163
Polysaccharide
No
Td ANTIGEN
164
Polysaccharide
Could be
Ti-1 ANTIGEN
Ti-2
ANTIGEN
165
Relative response time
Slow
Td ANTIGEN
166
Relative response time
Fast
Ti-1 ANTIGEN
Ti-2
ANTIGEN
167
Dominant Ab isotypes
IgG, IgE, IgA
Td ANTIGEN
168
Dominant Ab isotypes
IgM, IgG rarely
Ti-1 ANTIGEN
169
Dominant Ab isotypes
IgM, IgG
sometimes
Ti-2
ANTIGEN
170
Diversity of antibodies
High
Td ANTIGEN
171
Diversity of antibodies
Low
Ti-1 ANTIGEN
Ti-2
ANTIGEN
172
Stimulates immature and neonatal B cells
No
Td ANTIGEN
Ti-2 ANTIGEN
173
Stimulates immature and neonatal B cells
Yes
Ti-1 ANTIGEN
174
Polyclonal B cell
activator
No
Td ANTIGEN
Ti-2 ANTIGEN
175
Polyclonal B cell
activator
Yes
Ti-1 ANTIGEN
176
Memory B cells generated
Yes
Td ANTIGEN
177
Memory B cells generated
No
Ti-1 ANTIGEN
Ti-2 ANTIGEN
178
Magnitude of response upon a second exposure
Secondary response level
Td ANTIGEN
179
Magnitude of response upon a second exposure
Primary response level
Ti-1 ANTIGEN
Ti-2 ANTIGEN
180
Examples
Diphtheria toxin
Purified
Mycobacterium protein
Td ANTIGEN
181
Examples
Bacterial lipopolysaccharide
Ti-1 ANTIGEN
182
Examples
Pneumococcal polysaccharide
Ti-2 ANTIGEN
183
• Contain a molecular region that acts as a mitogen
Ti-1 antigens
184
– Molecule that non-specifically stimulates cells to initiate mitosis
mitogen
185
(?) binds to a surface receptor that is expressed by many cells, including B cells
Mitogen portion
186
• Simultaneously, the (?) bind to epitopes outside the mitogen region of the Ti-1 antigen
BCRs of the B cell
187
• The (?) sends a strong signal to the nucleus of the B cell to proliferate
mitogen receptor
188
• Many clones of naïve B cells can be activated at once by (?)
Ti-1 antigens
189
• Can also activate immature B cells and the B cells of
newborn children
Ti-1 antigens
190
• Found in many bacterial and viral structures and products
Ti-2 antigens
191
• Generally large polymeric proteins or polysaccharides (sometimes lipids or nucleic acids)
Ti-2 antigens
192
• Contain many repetitions of a structural element
Ti-2 antigens
193
– Acts as a multivalent antigen that can bind with high avidity to mIgM molecules in neighboring BCR
complex on the surface a B cell
Ti-2 antigens
194
– BCRs are said to be cross-linked
Ti-2 antigens
195
– Cannot activate naïve B cells in the absence of cytokines produced (mainly) by activated T cells
Ti-2 antigens
196
• The TCR of a T cell recognizes a complex composed of an MHC molecule bound to a peptide of an antigenic protein
Td antigens
197
For a Th effector cell to supply T cell help
to a B cell that has encountered an antigen, the (?) must
also have been activated by a peptide-MHC Class II complex derived from the same antigen
original naïve T cell
198
For a Th effector cell to supply T cell help
to a B cell that has encountered an antigen, the original naïve T cell must
also have been activated by a (?) derived from the same antigen
peptide-MHC Class II complex
199
Oral p.o. By mouth
MALT
200
INTRAVENOUS i.v. Into a blood vessel
Spleen
201
INTRAPERITONEAL i.p. Into the peritoneal cavity Spleen
Spleen
202
INTRAMUSCULAR i.m. Into a muscle
Regional lymph node
203
INTRANASAL i.n. Into the nose
MALT
204
SUBCUTANEOUS s.c. Into the fatty hypodermis layer beneath the skin
Regional lymph node
205
INTRADERMAL i.d. Into the dermis layer of skin
SALT
206
• Potential for antigen processing and
presentation
PROPERTIES OF Td ANTIGENS
207
• Produced in the spleen
Short-lived plasma cells
208
• Important for the very early stages of
the adaptive response against blood-borne Ti antigens
Short-lived plasma cells
209
• Have a half-life of 3 – 5 days
Short-lived plasma cells
210
• Secrete only low affinity IgM antibodies
Short-lived plasma cells
211
• Spherical or ellipsoidal
Long-lived plasma cells
212
• 10 – 20 mm in size
Long-lived plasma cells
213
• Presence of abundant cytoplasmic
immunoglobulin
Long-lived plasma cells
214
• Nucleus is eccentric or oval with heavily clumped chromatin that stains darkly
Long-lived plasma cells
215
• Most fully differentiated lymphocyte
Long-lived plasma cells
216
• Not normally found in the blood
Long-lived plasma cells
217
• Located in the germinal centers in the peripheral lymphoid organs
Long-lived plasma cells
218
• nondividing, after several days of Ab production, they die without further proliferation
Long-lived plasma cells
219
• Can secrete IgG, IgA and/or IgE antibodies
Long-lived plasma cells
220
• Enlarged rER and Golgi compartments and increased number of ribosomes
Long-lived plasma cells
221
• Express little or no CD40, MHC class II or mIg on their cell surfaces
Long-lived plasma cells
222
• No longer receive T cell help
Long-lived plasma cells
223
• Incapable of cell division
Long-lived plasma cells
224
• Produce high affinity Ab
Long-lived plasma cells
225
• Migrate from the germinal centers to the bm
also in the lymph node medulla or in the splenic red pulp
Long-lived plasma cells
226
• Up to 40% of the total protein synthesized by these mature cells is immunoglobulin
Long-lived plasma cells
227
(?) → transcriptional repressor which blocks the plasma cell differentiation pathway
Bcl-6
228
• Resemble naïve B cells in their small size
and general morphology but carry
different surface markers and have a longer life span (varies)
Memory B cells
229
• Also found in the germinal centers
Memory B cells
230
• Represent progeny of antigen-stimulated B cells that are capable of responding to antigen with increased speed and intensity
Memory B cells
