Functions of primary lymphoid organs
site of B and T lymphocyte development and education
provide a collection of T and B lymphocytes with receptors specific for diverse antigens for secondary lymphoid tissue
production/differentiation of dendritic cells from progenitor cells
central tolerance (render T and B cells tolerant to self antigens)
Which are primary lymphoid organs
Thymus (T-cells)
Ileal Peyer's Patches (B - cells)
Bursa (b-cells)
Bone Marrow
tonsil/spleen
Lymph and hemal nodes
Jejunal Peyer's patch
Which are secondary Lymph Tissues
Bursa (B-cells)
Tonsil/spleen
Jejunal Peyer's Patch
Lymph and Hemal nodes
Lymphoblasts invade the from the bone marrow where they become . These cells then mature to become .
There is a difference between immature and naive T-cells.
Immature t-lymphocytes are called .
Recognition of a self-major histocompatibility complex (MHC) molecule is ❌ selection. Elimination of a cell with high affinity for self peptides is ❌ selection. Death by neglect of cells that so not recognize their MHC is negative selection.
Expression of accessory molecules during thymocyte maturation 1) signaling component of T-cell receptor - ❌ 2) T-helper cells - ❌ 3) Cytotoxic T cells - ❌
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MHC class 1 binding leads to mature T cell MHC class 2 binding leads to mature T cell
Single-positive thymocytes leave the thymus as a single memory cell and are very important for viral immunity. (they are also more prevalent in pigs)
AIRE gene encodes for..
self peptides
insulin
thyroid hormone
collagen
T-cell receptors
B-cell receptors
() control expression of over 400 tissue specific proteins. They are expressed by cells with MHC molecules. genes are important for developing to become .
❌ - zinc containing peptide produced by thymic epithelial cells important for T- cell function. ❌ - regulate positive selection (produced from Hassall's corpuscles)
Zinc is not essential for T cells and skin enzymes.
Which are consequences of not having a thymus (mice and cats)
no T cells in secondary lymphoid tissue
No t cells in primary lymphoid tissue
no T cells in circulation
defective rejection of graft tissue
intact rejection of graft tissue
defective t cell mediated immunity
antibodies to protein antigen decreased, other antibodies are okay
Which of the following processes is preserved in nude mice or nude cats
graft tissue rejection
t cell immunity
circulating antibody levels
B lymphocyte concentrations
CD4 and CD8 lymphocyte concentration
Thymecotmy at birth in calves has little effect on T cell immunity compared to rodents because the thymus is fully developed at birth.
Where are B cells developed mainly for primates and rodents.
ileal peyer's patches
bursa
appendix
When is the Peyer's patch in the ileum involuted by
12 mo
11 mo
at birth
15 mo
When is the discontinuous jejunal peyer's patch involuted by?
it isn't - it is life long
What is the role of the bursa
generate BcR diversity
MHC expression
positive selection
What occurs within the cortex of the Bursa
stromal cells present self-antigens on surface receptors to B cells
negative selection of self reactive B cells
B cell proliferation and rearrangement of genes occurs
In the of the bursa, stromal cells present on the surface receptors (sIgM) to B cells. selection occurs when B cells are .
Effects of bursectomy or removal of ileal peyer's patch
total lymphocyte pool would slightly decrease
humoral immunity (antibody concentration markedly altered)
there would be no circulating T-lymphocytes
dendritic cells in tissues would decrease
Lymphocyte cones each have the same specificity for epitopes because there is not diverse set of genes.
What is gene rearrangement in primary or central organs unique to?
innate immune system
adaptive immune system
vertebrates
invertebrate
the insertion of upstream DNA or the addition of gene rearrangement (occurs in the bursa or its species equivalent -ileal peyer's patch-)
gene interconversion
gene mutation
gene conversion
gene morphing
Somatic hypermutation only happens to . It is a mutation that occurs in the centers during exposure.
What do each of the letters stand for when it comes to receptor chain regions (gene segments) V- D- J- c-
B cell receptor chains ❌ - VJC ❌ - VDJC
T-cell receptors chain pairs Gamma and Delta ❌ - VJC ❌- VDJC Alpha and Beta ❌- VJC ❌ - VDJC
When does receptor gene rearrangement occur in each lymphocyte?
during the mutation process
during the selection process
during the migration process
after each lymphocyte leaves and enters circulation
Receptor gene rearrangement is a random process (like shuffling cards).
RAG or 1 and 2, is a gene that initiates recombination.
Which of the following are members of the nonhomologous end joining (NHEJ) pathway of DNA repair?
RAG 1
TdT polymerase
Artemis
DNA dependent protein kinase, catalytic subunit (DNA-PKcs)
Which B cell chain rearranges first? (heavy or light)
heavy
light
The B cell gets a few tries to rearrange its heavy chain.
Which gene loops out a segment of DNA to be broken from the main segment for use in recombination?
RAG
TdT
RAG knows where to cut because the gene sequence has flanked by the gene segments.
❌ base pairs make about ❌ turn of the DNA helix. ❌ base pairs make about ❌ turns of the DNA helix.
The region begin targeted by RAG is flanked first by the conserved region, then comes the region (which is removed for the ), and finally the conserve region.
❌: movement of a cell in response to a chemical stimuli ❌: a family of cytokines with the ability to induce direct chemotaxis ❌: transmembrane cell adhesion proteins and signaling receptors (ex CD11b/CD18)
CCR7 is the cell receptor that interacts with the chemokine receptor for chemokines CCL and CCL which are both crucial for T-cell trafficking.
CXCR5 is a cell receptor that interacts with the chemokine CXCL to traffic B cells.
❌ cells take up bacterial ❌ in the skin (at the site of infiltration) and then move to enter a draining lymphatic vessels using ❌ to migrate. Antigen bearing dendritic cells enter the draining lymph nodes, where they settle in the ❌ areas.
Where do CCR7 naive and memory T-cells migrate.
LN follicle
Cortex
Paracortex
Where do CXCR5 presenting B-cells migrate?
paracortex
cortex
Where do CCR7 presenting dendritic cells migrate.
Which chemokines do dendritic cells use to migrate through tissues (3)
CCL19
CCL21
CXCL13
CXCL12
Hemolymph nodes contain B cells in cortex and T-cells at the center. They also have gamma/delta T cells.
function of splenic red pulp
filters blood
filters lymph
removes aged blood cells and immune complex coated cells by macrophages in sinus the red pulp
salvage iron and bilirubin from red blood cells
Functions of splenic white pulp
marginal zones - macrophage APC
follicles - B lymphocytes reside
periarteriolar sheath (PALS) - t cells
no high endothelial venules
The sinusoidal nonsinusoidal( sinusoidal, nonsinusoidal ) type of spleen has an abundance of venous sinuses which store large amounts of blood for quick release. It common in horses, dogs, and humans. The nonsinusoidal sinusoidal( nonsinusoidal, sinusoidal ) type of spleen has poorly developed sinuses. It is most prominent in cats and ruminants.
The spleen does not contract and the smooth muscle located around the ellipsoid capillary is used to control in and out flow.
Bone marrow can act as a secondary lymphoid organ by memory cell colonization, and a release of large quantities of antibodies in rodents and other species when a large dose of antigen is encountered.
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