Exam 2 Flashcards
Serum dilutions used to measure the amount of titer of Ab in serum
Titration
Measurement of the level of Abs in serum by testing dilutions of the serum for Ab reactivity
Titration
Inverse of the highest dilution of serum that gives a reaction in an immunological test
Titer
Lowest dilution which we still have a response
Titration
More diluted sample = more antibodies in serum initially
Titer
Amount of serum compared to total volume of dilution
Titration
1 ml of serum + 7 ml of diluent =
1:8 dilution
Common starting points for serial dilutions
1:2 and 1:10
Inverse of the highest dilution of serum giving a positive test result
Endpoint titer
____ = concentration of antibody
Titer
Which cat has the highest antibody concentration
Cat A 1:4 titer
Cat B 1:256 titer
Cat B 1: 256 Titer
Four fold rise or 2 serial dilutions in titer (or greater) from acute to convalescent serum indicates
active infection
Serum collected early after onset of illness
Acute serum
Serum collected 14-21 days later
Covalescent serum
T/F Acute and Covalescent samples must be tested in parallel
True
T/F Samples must be test by the same laboratory
True
Acute tier 1:8
Convalescent tier 1:32
Does this indicate active infection?
Yes
Measurement of single cells in a fluid stream
Flow Cytometry
3 important parts of Flow Cytometry
Size
Complexity
Fluorescence intensity
T/F Flow cytometry can be used on multiple sample types
True
Multiple sample types used in Flow Cytometry:
Bacteria or microorganisms
Latex beads or nanoparticles
Cells from peripheral blood, tissues, cerebrospinal fluid
Cluster of Differentiation (CD) molecules define
cell function/subtype
Monoclonal antibodies are available to what common CD molecules
Canine CD4
Bovine CD11c
T/F Flow cytometry can be used to determine the frequency of labeled populations
True
Antibodies can be conjugated to different ___
fluorescent markers
FSC=
cell size
SSC=
complexity
Green fluorescence is seen with what type of T cells
CD8+ cells
Orange fluorescence is seen with what type of T cells
CD4+ cells
Anti-CD8 linked to
fluorescein
Anti-CD4 linked to
phycoerythrin
B cell lymphomas with (high/low) MHC II co-expression have a better prognosis
High
Immunophenotyping (IP) identifies
leukocyte subsets
Red blood cell surface immunoglobulin for dog with IMHA
Anti-IgM (21%)
Anti-C3 (18%)
Anti-CD4 APC
Anti-IFN y
FITC
What T cell subset
Th1 cell
Anti-CD4 APC
Anti-IL-4
Pacific Blue
What T cell subset
Th2 cell
Define T helper lymphocytes by cytokine expression profiles
Intracellular Cytokine Staining (ICS)
T helper cells by cytokine expression does 2 things:
- Identify T cell subsets by fluorescent antibodies to surface CD molecules
- Permeabilize cells and add fluorescent antibodies to cytokines
Cytokine expression by memory lymphocytes to WNV vaccine antigens
Cytokine expressed by antigen stimulated CD4+ T cells
Phytohemagglutinin plays what role in testing WNV vaccine antigens
Positive control
Does the negative control for WNV vaccine antigen contain CD4+
No
What does the negative control contain
IFN-y
Heterogenous population is what type of lymphocytosis
reactive
Normal lymphocyte distribution is ____ T cells and ___ B cells
2/3
1/3
Antigen receptor (BCR/TCR) in reactive lymphocytosis is (clonal or polyclonal)
polyclonal
Many clones responding to an immunogenic stimulus
polyclonal
Homogenous population is what type of lymphocytosis
Neoplastic
Neoplastic transformation and proliferation of how many clones
Single
Antigen receptor (BCR/TCR) for neoplastic lymphocytosis is (polyclonal/clonal)
clonal
In health CD8 T cells should only account for approximately ___ % of T cells
20%
93% CD8 T cells would indicate
chronic lymphocytic leukemia
RID=
Radial Immunodiffusion
What is an acquired immunodeficiency with adult onset in a horse
CVID
Common Variable Immunodeficiency
CVID has what effects
B cell lymphopenia
hypogammaglobulinemia
Site of T and B lymphocyte development and education
primary lymphoid tissues
Primary lymphoid tissues provide _____ with receptors specific for diverse antigens for secondary lymphoid tissues
T and B lymphocytes
Render T and B cells tolerant to self antigens
Central tolerance
Central tolerance occurs in what tissues
Primary
Thymus
Primary
Bone Marrow
Primary and Secondary
Intestine
Primary in ruminants and horses
can be secondary
Spleen
Secondary
Lymph nodes
Secondary
Urogenital system
Secondary
Mammary glands
Secondary
Respiratory tract
Secondary
Salivary glands
Secondary
Source of stem cells
Fetal Yolk Sac
Fetal Liver
Bone Marrow
Sites of lymphocyte development and education
Thymus
Ileal Peyer’s Patches
Bursa
Bone Marrow
Primary or Secondary and B or T cells:
Thymus
Primary
T cells
Primary or Secondary and B or T cells:
Ileal Peyer’s Patches
Primary (ruminants and horses)
B cells
Primary or Secondary and B or T cells:
Bursa
Primary (birds)
B cells
Primary or Secondary and B or T cells:
Bone Marrow
Primary
B cells
Sites of foreign antigen interaction and proliferation
Tonsils Spleen Lymph nodes Jejunal Peyer's Patches (GALT) Mucosa-associated lymphoid tissue (MALT) Bone Marrow
Primary lymphoid organs: B cell development
Bone Marrow
Ileal Peyer’s Patches
Bursa
B cell development of Bone Marrow occurs in
Primates and rodents
B cell development of Ileal Peyer’s Patches occurs in
Ruminants and horses
B cell development of Bursa occurs in
Birds
The most important event in the development of a lymphocyte is
Generation of the antigen receptor
Membrane bound immunoglobulin (Ig)
BCR
Immunoglobulin structure of BCR includes
2 heavy chains (H)
2 light chains (L)
Linked by disulfide bonds
BCR has a signal transducing component consisting of
CD79
a and B chains
Within the cell membrane
Hallmark of humoral immunity is
specificity of the immune response due to gene rearrangment and somatic hypermutation
Random selection of gene segments resulting in genetic diversity of BCR (and TCR) occurs during
Lymphocyte development
Gene rearrangment occurs in (primary or secondary) lymphoid organs
primary
Random selection of gene segments resulting in genetic diversity of BCR and TCR occurs during lymphocyte development and is known as
Gene rearrangment
High frequency mutations in ___ region of Ig genes = Somatic Hypermutation
variable region
High frequency mutations in variable region of Ig genes occurs after what
B cell activation
High frequency mutations in variable region of Ig genes after B cell activation results in
increased affinity for antigen
Somatic hypermutation occurs in
mature lymphocytes in the germinal center of the lymph node
Somatic hypermutation occurs in (primary or secondary) lymphoid organs
Secondary
High frequency mutations in variable region of Ig genes after B cell activation resulting in increased affinity for antigen is known as
Somatic Hypermutation
Fc region includes
2 Constant Heavy regions
Fab region includes
1 Constant Heavy 1 Constant Light 1 Variable Heavy 1 Variable Light Antigen binding site
Biological activity occurs in which regions
Constant regions
2 types of Peyer’s Patches
Continuous
Discontinuous
Continuous Peyer’s Patches are in
The ileum
Continuous Peyer’s Patches involute by
15 months
Continuous Peyer’s Patches include B or T cells
B cells
Discontinuous Peyer’s Patches are in
Jejunum
Discontinuous Peyer’s Patches involute by
They don’t! They are life long
Discontinuous Peyer’s Patches have B or T cells
30% T cells
Continuous Peyer’s Patches are (primary or secondary) lymphoid organs
Primary
Continuous Peyer’s Patches are found in
Ruminants and horses
Discontinuous Peyer’s Patches are (primary or secondary) lymphoid organs
Secondary
Sites of rapid B cell proliferation
Continuous Peyer’s Patches
Continuous Peyer’s Patches reach maximal size and maturity when
Before birth
At the site of rapid B cell proliferation 2 things happen
- Most cells undergo apoptosis
2. Survivors released into circulation
T/F Bursa of Fabricius is only found in birds
True
What is the round sac located just above the cloaca
Bursa
What is the hollow sac with folds of epithelium containing lymphoid follicles
Bursa
When is the Bursa at its greatest size
1-2 weeks after hatching
THEN IT SHRINKS
Function of the Bursa
Generate BCR diversity
Structure of the Bursa
Follicular epithelium
Lymphoid follicles contain 2 parts
Cortex and Medulla
What happens in the cortex
B cells proliferate
Rearrangement of genes occur in which part of lymphoid follicles
Cortex
What part of the follicle is the pale center
Medulla
Negative selection of self reactive B cells (central tolerance) occurs in which lymphoid follciles
Medulla
What happens in the medulla
stromal cells present self antigens to B cells
If there is NO MHC expression there is no
Positive selection
Average percentages of B lymphocytes in blood
20%
Can breed differences account for inter-species variability in B cell percentages
Yes
B lymphocytes 7-30%
Dog
B lymphocytes 6-50%
Cat
B lymphocytes 17-38%
Horse
B lymphocytes 13-38%
Pig
B lymphocytes 11-50%
Sheep
B lymphocytes 16-21%
Cow
Bursectomy is the removal of
Ileal Peyer’s Patches
B cells constitute approximately what percentage of the circulating pool of lymphocytes
20%
During a Bursectomy the total circulating lymphocyte (t and B cells) pool slightly (increases or decreases)
decreases
During Bursectomy humoral immunity (antibody concentration) markedly (increases or decreases)
decreases
During Bursectomy which component markedly decreases
Antibody concentration
During Bursectomy which component slightly decreases
Total lymphocyte count
What is a lymphoepithelial organ
Thymus
What organ is located in anterior mediastinum over the heart
Thymus
The cortex is lymphocyte (rich/poor)
Rich
Thymic epithelium is visible in
Medulla
Cortex is (dark/light) area
Dark
Medulla is (dark/light) area
Light
Epithelial outgrowth of third pharyngeal pouch =
Thymic epithelial reticulum
Lymphoid progenitors from bone marrow migrate to thymus and become
Thymocytes
Thymocytes mature to
T lymphocytes
Where do lymphoid progenitors come from
Bone marrow
Lymphoid progenitors migrate to
Thymus
When Thymocytes mature to T lymphocytes what 3 things occur
- Develop T cell receptor (TCR)
- Become class restricted
- Tolerized to self
What is a heterodimer of 2 chains
TCR
which 2 components are prevalent in ruminants
Gamma and delta
which 2 components are most numerous
Alpha and beta
(Few/Many) genes encode for the antigen receptor
Many
Beta and delta chains have which regions
Variable (V)
Diversity (D)
Junctional (J)
Constant (C)
Which components have V, D, J and C regions
Beta and delta
V region
Variable
D region
Diversity
J region
Junctional
C region
Constant
Alpha and Gamma chains have which regions
Variable (V)
Junctional (J)
Constant (C)
Which components have V, J and C regions
Alpha and gamma
TCR =
antigen recognition
TCR co-receptor required for signal transduction
CD3
T cell development
1st step
Proliferate and rearrange TCR genes
Do delta,gamma and alpha, beta compete for expression
Yes
If gamma, delta is expressed what happens to the gamma, delta bearing TCR
Leaves the thymus
If alpha, beta is expressed what happens
Surface molecules are expressed on developing thymocytes
CD3
Co-receptor
Double positive
CD4 and CD8
Where are T cells educated
Thymus
Thymocyte proliferation and TCR development occurs in
Cortex
Positive selection =
Class Restriction
Negative selection =
Self-Tolerance
What happens when T cells recognize antigens presented by thymic epithelial cells on MHC class I or class II molecules
Class Restriction
Cells with TCR that can bind MHC plus Ag are (positively or negatively) selected in the thymus
Positively
Positive selection occurs where
Thymus
Cells lacking TCR capable of binding to MHC peptide undergo
apoptosis
Approximately what percentage of T cells die in the thymus
98%
A huge diversity of TCRs are possible, what proportion of these will bind to self-MHC
Small proportion
Receptor binds self peptide: self MHC class I
Matures to CD8+ T cell
Receptor binds self-peptide: self-MHC class II
Matures to CD4+ T cells
Class restriction =
Binding to MHC I or II leads to CD8 or CD4 T cell subset
Double positive thymocytes
self peptide binds to self MHC class
Single positive thymocytes
CD8 or CD4
CD8 cells are
Cytotoxic
CD4 T cells are
Helper cells
What is the exception in CD4+CD8+ in circulation
Pigs possess up to 60%
T cells must not respond to self antigens during (positive or negative) selection
Negative selection
T cells with TCR that can bind self MHC plus self Ag are
Negatively selected
Negative selection occurs where
Thymus
Negative selection is similar to central tolerance in B cells in which way
Deleted by apoptosis
Cells that successfully emerge from the thymus are
self tolerant
Goldilocks principle refers to
T cell selection
Too weak of binding to self peptide
cell dies
Too strong of binding to self peptide
Cell dies
Binding to self peptide presented on MHC molecules must be
Just right
Moderate binding
Cell lives
What gene encodes for self peptides
AIRE
Examples of AIRE gene
Insulin
Thyroid hormone
Collagen
AIRE stands for
Autoimmune regulator gene
What controls expression of >400 tissue specific proteins
AIRE
AIRE gene is expressed by what cells within MHC molecules
Thymic medullary epithelial cells
AIRE gene is important for developing thymocytes to become
self-tolerant
What happens to individuals that lack AIRE gene
Autoimmune Polyendocrinopathy Polyglandular autoimmune syndrome
Cortical epithelial cell mediates
positive selection
Cortical epithelial cell mediating positive selection =
MHC class restriction
Dendritic cell mediates
Negative selection
Dendritic cell mediating negative selection =
Self tolerance
What happens when TCR genes rearrange
Receptor is expressed
Earliest lymphocyte precursors enter the thymus in the
Medulla
After lymphocyte precursors enter the thymus in the medulla they move toward
Cortex
In the cortex lymphocytes proliferate and mature into
double positive (CD4+ CD8+) thymocytes
When they proliferate and mature into double positive thymocytes they generate a
TCR
Thymocytes are screened by
Positive (class restriction) and negative (self tolerance) selection
Where does thymocyte screening occur
Thymic cortex
Cortico-medullary junction contains mature
single positive (CD4 or CD8) T cells
Single positive T cells leave
Thymus
When T cells leave the Thymus they enter
Blood stream
Average percentages of T cells in blood of adult animals
50-65%
T cells 31-89%
Cat
T cells 46-72%
Dog
T cells 38-66%
Horse
T cells 45-57%
Pig
T cells 56-64%
Sheep
T cells 45-53%
Cow
Do breed differences count for differences in percentages within a species
Yes
Thymus involution occurs when in mice
within 3 weeks
Thymus occurs when for humans
During puberty
what happens when the thymus is involuted
replaced by fat but small amounts of functional lymphoid tissue remain
Mice thymectomized at birth have what 2 things occur
- Susceptible to infection
2. Fail to grow
Gene mutations resulting in absent or deteriorated thymis
Nude mice
Nude mice have what 5 issues
- No T cells in secondary lymphoid tissues
- No T cells in circulation
- Defective rejection of graft tissue
- Defective T cell mediated immunity
- Antibodies to protein antigens decreased (other antibodies OK)
Develops late in fetal life and persists life-long
Secondary lymphoid tissue
Facilitate antigen trapping
Secondary lymphoid tissue
Collects anitgen presenting cells (dendritic cells) and lymphocytes
Secondary lymphoid tissue
Support clonal expansion of antigen specific T and B lymphocytes (lymphopoiesis)
Secondary lymphoid tissue
In secondary lymphoid tissue antigen specific T and V cell effectors move where
Tissues
Secondary lymphoid tissues retain antigen specific
Memory cells
2 types of secondary lymphoid tissues
Encapsulated
Unencapsulated
Encapsulated secondary lymphoid tissues include
Lymph nodes
Spleen
Hemolymph nodes/hemal nodes
Unencapsulated secondary lymphoid tissues include
MALT
BALT
GALT
Tonsil
MALT
Mucosal lymphoid tissue
BALT
Bronchial associated lymphoid tissue
GALT
Get associated lymphoid tissue
T cell clonal proliferation occurs in
Paracortex
B cell clonal proliferation occurs in
Germinal Center
Naive cells enter lymph node through
HEV
What flows in lymph
Ag, APC drainage from inflammed tissues
Follicle with germinal center is CD3 positive or negative
Negative
Paracortex (T cells) and Immunohistochemistry with CD3 antibody labels what cells
T cells
Reactive lymph nodes have smaller or larger follicles
Larger
Reactive lymph nodes also show what due to larger follicles
Germinal centers
What are the 2 types of lymph nodes
Quiescent
Reactive
How does antigen get to lymph node to stimulate an immune response
DC take up bacterial antigens in the skin and enter a draining lymphatic vessel
After DC enter draining lymphatic vessels then what
DC bearing antigen settle in T cell areas
Lymph flow and Ag, APC drainage from inflamed tissues enters
Afferent lymphatics
After Naive T and B cells circulating in blood enter the lymph node via HEV they
Seek their antigen in the paracortex
T and B effector cells and antibodies leave via
efferent lymphatics
After effector cells leave efferent lymphatics where do they go
through thoracic duct and into systemic circulation
If native lymphocytes in HEV encounter antigen they are
activated
Once lymphocytes are activated what happens
leave the lymph node
Lymphoctes leave the lymph node as
effector lymphocytes
Effector lymphocytes leave through
thoracic duct
Effector lymphocytes can leave circulation and go to
tissues
Primed lymphocytes to got
Antigen
Naive lymphocytes go to
Arteries
Migration to the lymph node through HEV is regulated by
chemokines and adhesion molecules
Movement of a cell in response to a chemical stimulus
Chemotaxis
Family of cytokines with the ability to induce directed chemotaxis
Chemokine
Chemokines tell cells
where to go
Cytokines tell cells
what to do
Transmembrane cell adhesion proteins and signaling receptors
Integrins
Examples of Integrins
CD11b
CD18
___ are sticky for naive lymphocytes
HEV
HEV allow only _____ into lymph nodes
lymphocytes
L selectin is on
Lymphocyte
CD34 is on the
endothelium
L selectin is what CD molecule
CD62L
L selectin on lymphocytes bind to what
CD34
HEV have what type of endothelium
Cuboidal
Intracellular Adhesion Molecule 1
ICAM1
Leukocyte Functional Antibody 1
LFA1
When CD62L (L selectin) interacts with CD34 or GlyCAM1 on HEV it causes (loose or tight adhesion)
Loose adhesion
LFA1 binds tightly to
ICAM1
When LFA1 binds tightly to ICAM1 it causes
Tight adhesion and diapedesis
CCR7 homes T cell and DC to
CCL19 and CCL21
CCL19 and CCL21 are expressed in the
Paracortex
CXCR4 on DC homes to
CXCL12
CXCL12 is expressed in the
Paracortex
CD62L is on T cell or DC cell
T cell
CXCR4 is on T cell or DC cell
DC cell
CCR7 is on T cell or DC cell
Both
CCR7 corresponds to what CC on Paracortex
CCL19 and CCL21
CXCR4 corresponds to what CX on paracortex
CXCL12
Effector T cells shed
CD62L and CCR7
Why do T cells shed CD62L and CCR7
To get into peripheral tissues where inflammation is
T cells recirculate through blood and peripheral lymphoid tissues every
12-24 hours
T cells enter a lymph node across HEV in the
Cortex
T cells monitor antigen presented by
Macrophages and dendritic cells
T cells that do not encounter specific antigen leave the node via
Efferent lymph
T cells that encounter specific antigen proliferate and differentiate to
effector cells
Naive B cells loop through lymphoid system for up to ___ days
100 days
Naive B cells loop through lymphoid system seeking
antigen
Naive B cells receive ______ on each pass through the lymph node follicle
survival signals
Chemokine CCL21 attracts what cells to HEV
Immature B cells
Chemokines ___ and ___ attract B cells into lymph node
CCL21 and CCL19
Chemokine ___ attracts B cells into the primary follicle
CXCL13
CXCL13 attracts B cells into the
Primary follicle
CCR7 on B cells homes through HEV to ___ and ____ in paracortex
CCL19 and CCL21
CXCR5 on B cells homes to ___ in lymph node follicle
CXCL13
CXCL13 is located where
Lymph node follicle
B cell has CD62L and ___
CXCR5
Lymphocytes migrate to the
Lymph node
Where do naive T cells come from
Thymus
Where do naive B cells come from
Bone marrow
Peyer’s Patches
Bursa-birds
How does DC and ag enter the lymph node
Peripheral tissues
Diapedesis into lymph node and follow chemokine gradient
Naive CD4 T cells are activated by
Antigens
Antigens that activate Naive CD4 T cells are presented by
DC in lymph node
Naive B cells activated by antigen are trapped where
T cell zone of the lymph node
Naive B cells are trapped in what zone of the lymph node
T cell zone
Antigen-activated B cells present antigen to
Helper T cells
When B cells present antigen to helper T cells it forms what
cognate interactions and conjugate pairs
Recirculating naive T cells enter the which part of the lymph node
Paracortex
How do naive T cells enter the lymph node
HEV
T cells that encounter specific antigen on DC proliferate and differentiate to
TH subtype
TH subtype is dependent on
DC secreted cytokines
Circulating naive B cells enter which part of the lymph node
Paracortex
How do naive B cells enter the lymph node
HEV
B cells that encounter their antigen stay where
T cell zone
B cells that encounter their antigen process antigen to present to
T cells
How do B cells present to T cells
Peptide on MHC II
B cell zone is where
Follicle
T cell zone is where
Paracortex
TH cells and B cells specific for antigens on the same pathogen form
Conjugate pairs
B cells and T cells recognizing different epitopes on the same antigen =
cognate interaction
4 steps in the lymph node follicle of a reactive lymph node
- B cell activation
- Somatic hypermutation
- Affinity maturation
- Isotype (class) switch
Naive B cells are located in what zone
Mantle Zone
Germinal Center B cells undergo proliferation and
Somatic hypermutation
Germinal Center B cells are located in what zone
Dark Zone
Interactions with FDC causes
Affinity maturation
Interactions with FDC are located in what zone
Light Zone
Ig class switching and memory B cell formation are located in what zone
Light Zone
What is needed for class switching
Cytokines
What lymph nodes are inside out
Pig
What 4 other animals have inside out lymph nodes
Elephants
Rhinos
Hippos
Dolphins
Why are pig lymph nodes inside out
They do not have lymphocytes in pig lymph
Pig lymph node steps
Bloodstream
HEV
Lymph node paracortex
Efferent vein
Other mammals
Bloodstream HEV Lymph node paracortex Efferent lymphatics Thoracic duct
Hemolymph also known as
Hemal node
Hemal nodes are what color
Dark red or brown
What is the most prominent in ruminants and deer
Hemal node
Hemal nodes are scattered among blood vessels and function to do what
Filter blood and substances in circulation
Hemal nodes contain B cells where
Cortex
Hemal nodes contain T cells where
Center
Hemal nodes also have what type of cells
gamma, delta
Spleen contains what 2 pulps
Red
White
Which pulp filters blood rather than lymph
Red pulp
Red pulp removes _______ and immune complex coated cells
Aged blood cells
How does Red pulp remove cells
Macrophages
Where are the macrophages located in the red pulp which remove the cells
Sinus
Red pulp salvages _____ and ____ from red cells
Iron
Bilirubin
What pulp has a marginal zone-macrophages (APC)
White pulp
In white pulp what cells reside in follicles
B lymphocytes
Which pulp contains PALS
White pulp
PALS
Periarteriolar sheath
What cells do PALS contain
T cells
White pulp does not have
HEV
Sinusoidal type of spleen has (abundant or poor) sinuses
Abundant
What type of sinuses do sinusoidal types contain
venous
Which animals store large amounts of blood for quick release
Horse
Dog
Human
Where do animals store large amounts of blood for quick release
Sinusoidal Type of Spleen
Horses, dogs and humans can do what during exercise
Splenic contraction
What type of spleen has smooth muscle around ellipsoid capillary
Sinusoidal type
Smooth muscle around ellipsoid capillary is most prominent in
Horses
Nonsinusoidal type spleen have (abundant or poor) sinuses
Poorly developed
Nosinusoidal type are most common in
Cats
Ruminants
Urogenital is (primary or secondary) lymphoid tissue
Secondary
Where do memory cells and plasma cells colonize
Bone Marrow
Can Bone Marrow act as a secondary lymphoid tissue
Yes
Second dose of antigen causes bone marrow to release large quantities of
Antibodies
Second dose of antigen causes bone marrow to release large quantities of antibodies in which animals
Rodents
Second dose of antigen causes what to release antibodies
Bone Marrow
Thymus : Classification Source of Immune Cells Interact with Foreign antigen Interact with Self antigen Positive or negative selection
Primary T cells N Y Positive and Negative
Bursa: Classification Source of Immune Cells Interact with Foreign antigen Interact with Self antigen Positive or negative selection
Primary (Birds) B cells N Y Negative only
Ileal Peyer's Patches: Classification Source of Immune Cells Interact with Foreign antigen Interact with Self antigen Positive or negative selection
Primary (Ruminants, Horses) B cells N Y Negative only
Bone Marrow: Classification Source of Immune Cells Interact with Foreign antigen Interact with Self antigen Positive or negative selection
Primary and Secondary Lymphoid progenitor B cells Y Y Negative only
Jejunal Peyer's Patches: Classification Source of Immune Cells Interact with Foreign antigen Interact with Self antigen Positive or negative selection
Secondary Neither Y N N
Lymph Nodes: Classification Source of Immune Cells Interact with Foreign antigen Interact with Self antigen Positive or negative selection
Secondary Neither Y N N
Spleen: Classification Source of Immune Cells Interact with Foreign antigen Interact with Self antigen Positive or negative selection
Secondary Neither Y N N
Intracellular protozoan parasite
Leishmania sp.
Leishmania parasite is taken up by
Macrophages
Leishmania is transmitted by
Sand flies
Is Leishmania endemic in many countries?
Yes
Where is it comon
South/central America
Africa
Asia
Southern Europe
What causes a disseminated infection in dogs and humans
Visceral Leishmaniasis
What causes the dog not to mount good cell mediated immunity
Visceral Leishmaniasis
Leishmania has a high incidence in what breeds
Foxhounds
Breeds in Spain and France
Leishmania has clinical signs of
Enlarged lymph nodes
Hepatomegaly
Splenomegaly
Resistant individuals develop ___ which resolves
Cutaneous form
What step of the Leishmania life cycle is this:
Promastigote stage in Sandfly gut migrates to proboscis and is injected into skin during blood meal
1
What step of the Leishmania life cycle is this:
Promastigotes taken up by Macrophages and transforms into Amastigote stage
2
What step of the Leishmania life cycle is this:
Sandfly takes blood meal and ingests infected macrophages
3
what step of the Leishmania life cycle is this:
Amastigotes transform into Promastigotes
4
Leishmania life cycle basic points:
- Promastigote injected into skin
- Promastigotes taken up b macrophages
Transforms into Amastigote stage - Sandfly ingests infected macrophages
- Amastigotes transform to Promastigotes
Susceptible dogs have 3 major changes
- Defect in the NRAMP gene
- Helper cells do not produce IFN y
- High concentration of antibody
NRAMP
Natural Resistance Associated Macrophage Protein
Defect in NRAMP was reported in dogs from where
Spain and France
Helper cells do not produce IFN y following what
Stimulation by Leishmania antigen
High concentration of antibody against Leishmania is present where
In the blood
What does NRAMP do
Transports divalent ions
Transports divalent ions Fe2 out of the phagosome
NRAMP
Fe out of the phagosome competes with
Bacteria’s siderophore pump
NRAMP transports divalent ions out of where
Phagosome
Important parts of Leishmania infection to consider
- Macrophages
- Antigen/antibodies
- Complement system
- Serolgy: Application of antigens and antibodies
What immune mechanism plays a protective role against Leishmania
Macrophages and NRAMP
INF y brings in M1 activating macrophages
Why are liver, spleen and lymph nodes the principle organs enlarged
They are the primary organs of pathogen clearance
Recruit inflammatory molecules
How does a defect in NRAMP decrease the innate immune response to the parasite
Ability of the macrophages to fight phagocytosed microbes is reduced
Which stage of Leishmania (Promastigote or Amastigote) would be most susceptible to antibody and/or complement activation
Promastigote
Extracellular stage
What role does IFN y play in macrophage defenses against the intracelluar stage of the parasite
Critically needed to activate macrophages to differentiate into
- M1 Macrophages: NO production/ROS/Lysozyme/Elastase
- Lack of IFN y -Inefficient/Ineffective Macrophage actiation
2 tests that can be used to confirm Leishmania infection
PCR: Parasite SNA
IFA/Flow Cytometry: Presence of parasite
ELISA/Agglutination test/Western Blot-Anti-promastigote antibodies
Major Histocompatibility Conplex was discovered based on
Graft Acceptance or Rejection
Graft acceptance or rejection represents
self recognition
Cluster of closely linked genes
Locus
Locus of genes control presentation of ___ in APCs
Protein Antigens
what controls presentation of protein antigens in APCs
Locus
What is the requirement for peptide to be bound in an MHC molecule to elicit an immune response
MHC restriction
MHC restriction requires peptide to be bound to
MHC molecules
Peptide bond to MHC molecule elicits what
An immune response
Antigen Presenting Cells use ____ to bind and present antigens
Receptors called MHC molecules
APCs do what
bind and present antigens
what receptors do APCs use
MHC molecules
MHC molecules are encoded by genes located within the
Major Histocompatibility Complex
Classical MHC molecules are (highly or very little) polymorphic
Highly
Enormous variety of inherited structural variations that permit each individual animal to respond to different antigens
Polymorphic
Inherited structural variations
Classical MHC molecules
what permit each individual animal to respond to different antigens
Classical MHC molecules
Class I MHC molecules are found on
all nucleated cells
Function of Class I MHC molecules
present endogenous antigens to CD8+ T cells
what class of MHC molecules present endogenous antigens to CD8+ T cells
Class I
Class II MHC molecules are largely restricted to
professional APCs
(Dendritic cells)
(Macrophages)
(B cells)
Function of Class II MHC molecules
Present exogenous antigens to CD4+ T cells
What class of MHC molecules present exogenous antigens to CD4+ T cells
Class II
Class III MHC are (classical or non-classical)
Non-classical
Which class of MHC contains a mixture of genes, some of which encode complement components
MHC III
Function of Class III MHC
Encode complement components
3 major classes of genes located within the MHC grouped in regions
Class I
Class II
Class III
MHC molecules are grouped together by
regions
What class has receptors for endogenous antigen found on most nucleated cells
Class I
What class has a mixed group of proteins including some complement components
Class III
What class has receptors for exogenous antigen predominantly found on antigen presenting cells
Class II
T/F Arrangment of gene regions within MHC is different for different species
True
ELA
Horse
BoLA
Bovine
SLA
Pig
CLA
Dog
FeLA
Cat
H2 in mice
Rodent
HLA
Primate
II, III, I -centromere
Horse
ELA
centromere-IIb, IIa, III, I
Bovine
BoLA
II, centromere- III, I
Pig
SLA
Centromere-II, III, I
Dog
CLA
II, III, I centromere- I
Cat
FeLA
Centromere-I, II, III, I
Rodent
H-2 in mice
Centromere- II, III, I
Primate
HLA
Function of MHC Molecules
Display cell-associated linear peptides for recognition by T cells
Both self peptides and foreign peptides regulate
Immune responses
Will foreign antigen that cannot bind MHC trigger adaptive immunity
No
CD4+ T cell + Antigen =
T cell response or not
No response
CD4+ T cell + Antigen + APC=
T cell response or not
Yes
In order for T cells to have a response they need
APC
T cells recognize _____ presented in the context of self MHC
Epitope
MHC has what 2 important features for binding with T cell receptor
Anchor residue of peptide
Pocket of MHC
____ molecules are membrane bond
MHC
Recognition by T cells requires _____ and ____
Cell-cell contact
Peptide
MHC class I present _____ to CD8+ T cells
cytosolic peptides
What MHC class can bind peptides 8-11 amino acids long
Class I
MHC class II present peptides generated from extracellular antigens to ___ cells
CD4+ T cells
MHC class II present peptides generated from _____ antigens to CD4+ T cells
Extracellular antigens
What MHC class binds peptides 10-30 amino acids long
Class II
What 2 things are required for Class MHC and CD T cells to bind
CD3
TCR
Which MHC class are the ends of the peptide in extended conformation and trimmed
Class II
MHC II binding pockets are (more/less) permissive
More
MHC molecule can present how many peptides at a time
One
Do MHC molecules have broad specificity
Yes
MHC molecules is capable of presening (different/same) peptides at (different/same) time
Different
Different
______ are critical amino acids which must fit into the binding pocket
Anchor residues
____ sequence between anchors can vary
Peptide
T/F number of amino acids between anchors can vary
True
MHC Polymorphism affects ______
Peptide binding
Changes in the pockets, walls and floor of the peptide binding cleft alter____
peptide MHC interactions
Change in pockets, walls and floor of the peptide binding cleft alter peptide MHC interactions and determine ____
which peptides bind
Products of different MHC alleles bind (different/same) repertoire of peptides
Different
Which MHC class has 3 alpha segments and B2 microglobulin
Class I
Peptide binding cleft in MHC Class I is between what segments
Alpha 1 and Alpha 2
What MHC class has 2 alpha segments and 2 B segments
MHC class II
Peptide binding cleft in MHC Class II is between what segments
Alpha 1 and Beta 1
Transmembrane region has N or C terminus
C
Which MHC Class has loci A, B and C
Class I
Which MHC Class has loci DP, DQ, DR
Class II
Class I is distributed to what kind of cells
Most nucleated cells
Class II is distributed to what kind of cells
B cells
Macrophages
Dendritic cells
Function of Class I molecules
Present antigen to CTLs
Function of Class II molecules
Present antigen to T helper cells
What class has the result of T cell mediated toxicity
Class I
What class has the result of T cell mediated help
Class II
What is the different versions of each gene among individuals called
Allele
Group of genes inherited as a set is known as
Haplotype
(Heterozygous/ Homozygous) has 6 molecules on the surface
Heterozygous
(Heterozygous/Homozygous) has 3 molecules on the surface
Homozygous
Heterozygous animals with 2 MHC alleles coded for at each locus express ____ different antigen presenting molecules on the cell surface
6
Heterozygous or Homozygous generate a more diverse and effective immune response
Heterozygous
Homozygous animals have only 1 MHC a ____ allele coded for at each locus
single
Stable MHC I expression on the cell surface requires
a chain
B2 microglobulin
bound antigenic peptide
Most individuals are (heterozygous/homozygous) for MHC genes
Heterozygous
MHC Class I express ___ different class I molecules on every cell containing alpha chains encoded by the 2 inhereted alleles
6
MHC class I contains alpha chains encoded by the 2 inherted alleles of
HLA-A
HLA-B
HLA-C
Antigen binding site of Class I is formed by the folding of
Alpha 1 and Alpha 2 domains
B2 microglobulin parallels which alpha chain
Alpha 3
