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100 Cards in this Set

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Lymph node:
What is it?
What is the role of the follicle?
what is the role of the Medulla?
What is the role of the paracortex?
2ndry organ with many afferents, 1 or more efferents, encapsulated with trabeculae. non specific filtration by macrophages, storage/proliferation of B and T cells, Ab production
Follicle- B-cell localization and proliferation. Outer cortex- 1ry follicles are dense and dormant. 2ry follicles have pale central germinal centers and are active
Medulla- medullary cords- closely packed lymphocytes and plasma cells. Communicate with efferent lymphatics and contain reticular cells and macrophages.
Paracortex- Houses T cells. Region of cortex between follicles and medulla. High endothelial venules through which T and B cells enter from the blood. In extreme cell immune response, paracortex becomes greatly enlarged. Not developed in DiGeorge
What is different about the R arm and R half of the head in lymph drainage?
Drains to the Right lymphatic duct. Everything else goes to the thoracic duct.
Where are T-cells found in the spleen?
periarterial lymphatic sheath and red pulp of the spleen.
Where are B-cells found in the spleen?
follicles and white pulp of the spleen.
Describe the sinusoids of the spleen
Long vascular channels in red pulp with fenestrated barrel hoop basement membrane. Macrophages are nearby.
What si the role of the thymus?
T-cell maturation. Encapsulated.
From epithelium of 3rd branchial pouch.
Lymphocytes are of mesenchymal origin.
Cortex is dense with immature T cells; medulla is pale with mature T cells. Epithelial reticular cells and contains Hassall's corpuscles. Posititve selection (MHC restriction) and negative selection (nonreactive to self) occur at the corticomedullary junction.

Immature T cells in the cortex
mature in the medulla.
What is the role of Th1 cells?
make IL 2 and gamma-IFN- activate macrophages (increase killing efficiency of intracellular bacteria) and Tccells
What is the role of Th2 cells?
IL-4,5
help B cells make antibody.
What induces transformation to Th1
IL 12- secreted by macrophage
What induces transformation to Th2
IL 4
What is the major function of B cells?
Ab-mediated immunity
Host defense against infection (opsonize bacteria, neutralize toxins and viruses)
Allegry- hay fever, type I hypersensitivity
Autoimmunity
What is the major function of T cells?
Host defense against infection - TB, virus, fungi
Allergy- type IV hypersensitivity
Graft and tumor rejection
Regulation of Ab response- help and suppression
What are the differences between MHC class I and II?
class I-
all nucleated cells
1 polypeptide, B2-microglobulin
loading in RER
bind to CD8

Class II-
macrophages, dendritic cells, B cell, and other Ag presenting cells.
major cause for organ rejection
Alpha and Beta chain, 2 polypeptides
loading in acidified endosome
CD4 cells.
T helper cells:
What cytokines does it secrete and for what purpose?
IL-2, to self and to make CD8s
IL2,4,5- B-cells
How are helper-T-cells activated?
foreign body is phagocytosed by APC
Foreign Ag is presented on MHC II adn recognized by TCR on Th cell
Costimulatory signal by B7, CD28
Th cell activated to produce IL2 and gamma-IFN.
How are cytotoxic T-cells activated?
Endogenous proteins are presented on MHC I and recognized by TCR.

IL-2 from Th cell activates Tc to kill
What are the roles of the variable and constant parts of Abs?
Variable recognize Ags, constant part of heavy chain fixes complement.
What are the four Cs of Fc?
Constant
Carboxy terminal
Complement-binding
Carbohydrate side chain
What roles do Abs perform?
opsonization
neutralization
complement activation
How is Ab diversity created?
Recombination of VJ (light chain) or VDJ (heavy chain)
Somatic hypermutation
Addition of nucleotides to DNA during "genetic recombination" by terminal deoxynucleotidly transferase.
What is IgG good for?
2ry response
most abundant
fixes complement
crosses the placenta
opsonizes bacteria
neutralizes bacterial toxins and viruses
What is the role of IgA?
Prevents attachment of bacteria and viruses to mucous membranes.
Does not fix complement
monomer or dimer
found in secretions
picks up a secretory component from epithelial cells
What is the role of IgM?
1ry response
fixes complement but does not cross the placenta.
Ag receptor on teh surface of B cells
What is the role of IgD?
unclear
surface of many b cells
What is the role of IgE?
Mediates type I hypersensitivity by inducing hte release of mediators from mast cells and basophils when exposed to allergens.
Define:
Allotype
Isotype
Idiotype
Allotype- polymorphism of Ig. can be on light or heavy chain
Isotype- G vs. M, heavy chain
Idiotype- Specific for every Ag. Determined by Ag binding. Each is unique.
Pneumonic for IL 1-5
Hot T-Bone stEAk
1- hot- fever
2- T-cells
3- stimulates bone marrow
4- IgE production
5- IgA production
IL 1:
what secretes it?
What does it do?
Secreted by macrophages
stimulates T cells, B cells, neutrophils, fibroblasts, and epi cells to grow, differentiate, and produce
IL 2:
what secretes it?
What does it do?
Secreted by Th cells
stims growth of helper and cytotoxic Ts
IL 3:
what secretes it?
What does it do?
Secreted by activated T celss
Growth and diff of BM stem cells- similar to GM-CSF
IL 4:
what secretes it?
What does it do?
Secreted by Th cells
growth of B
class switching in IgE and IgG
IL 5:
what secretes it?
What does it do?
Secreted by Th cells
B cells
Switching of IgA
Stims production and activation of eos
IL 6:
what secretes it?
What does it do?
secreted by T cells and macrophages
Production of acute-phase reactants and immunos
IL 8:
What does it do?
Chemotaxin for neutrophils
IL 10:
what secretes it?
What does it do?
Th2
stims 2, inhibs 1
IL 12:
what secretes it?
What does it do?
macros and B-cells secrete
activate Nks and Th1s
gamma-IFN:
what secretes it?
What does it do?
Th cells
stims macrophages
TNF alpha:
what secretes it?
What does it do?
secreted by macrophages
Increases IL-2 receptor synth by Th cells. Increase in B-cell prolif. Attracts and activates neutrophils. Stims dendritic cell migration to lymph nodes.
What are the cell surface proteins of Helper Ts?
CD 4, TCR
CD 3, 28, 40L
What are the cell surface proteins of Cytotoxic Ts?
CD 8, TCR
CD3
What are the cell surface proteins of B cells?
IgM, B7, CD19, CD20, CD40, MHC II
What are the cell surface proteins of Macrophages?
MHC II, CD14
Fc, C3b receptors
What are the cell surface proteins of NK cells?
Receptors for MHC I, CD16
What is the role of IFNs?
they put uninfected cells in an antiviral state. induce production of a proteint that inhibs viral sythesis by degrading viral mRNA.
alpha- inhib viral
gamma- Increases MHC I and II expression
activate NK cells.
What is the role of complement?
hmoral immunity and inflammation
defends against G-s.
Activated by IgG IgM in classic
activated by microbe molecules in the alternate pathway.
What is the role of C1,2,3,4?
viral neutralization
What is the role of C3b?
opsonization
what is the role of C3a, C5a?
anaphylaxis
5a also chemotaxis for neutrophils
What is the role of C5a?
chemotaxis for neutrophils
anaphylaxis
What is the role of C5b-9?
cytolysis by the MAC
What happens in a deficiency of C1 esterase?
angioedema- overactive complement
What happens in a deficiency of C3?
severe, recurrent pyogenic sinus and respiratory tract infections
What happens in a deficiency of C6-8?
Neisseria bacteremia
What happens in a deficiency of decay-accleerating factor (DAF)?
paroxysmal nocturnal hemoglobin
What is the difference between passive vs. active immunity?
Active- induced after exposure. slow onset, long-lasting
Passive- based on getting Abs from another host- rapid, short-lasting
When do you give Ig?
To Be Healed Rapidly
Tetanus
Botox
HBV
Rabies.
What are some examples of Ag variation?
Bacteria-
Salmonella- (two flagellar variants)
Borrelia (relapsing fever)
Neisseria gonorrhoeae- pilus protein
Virus- Flu
Parasites- Trypanosomes (programmed)
what happens in anergy?
self-reactive T and B cells aren't co-stimulated. They are then destroyed.
What is type I hypersensitivity?
Anaphylactic and atopic
Ag cross links IgE on mast cells and basophils-> histamine release.

anaphylaxis, asthma, hives, local wheal and flare

First and Fast- Ab mediated
What is type II hypersensitivity?
Ab mediated
IgM, IgG bind to antigen on "enemy" cell, leading to lysis (by complement) or phagocytosis.

Autoimmune hemolytic anemia, Rh disease, Good pasture's, rheumatic fever, Graves' disease, bullous pemphigoid, MG, ITP

Cy-2-toxic
complement- MAC
What is type III hypersensitivity?
Immune complex- Ag-Ab complexes activate complement-> neutrophils
PAN, Glomerulonephritis, SLE, RA

Serum sickness- Abs to foreign protein are produced (5 days)-> immune complex
Caused by drugs. Fever, urticaria, arthralgias, proteinuria, lymphadenopathy

Arthus reaction- local subacute Ab. Intradermal injection of Ag-> Abs-> complexes in the skin
Edema, necrosis, activation of complement
Farmer's lung, thermophilic actinomycetes.
What is type IV hypersensitivity?
Delated type. Sensitized T-cells encounter Ag-> macrophage activation
Involved in Transplant, TB skin tests, Touching (contact dermatitis)
Anti-ANA
SLE
Anti-dsDNA
SLE (specific)
Anti-smith
SLE (Specific)
Antihistone
Drug induced lupus
Anti-IgG (rheumatoid factor)
RA
Anti-neutrophil (C-ANCA, p-ANCA)
vasculitis
anti-centromere
CREST
anti-Scl-70
scleroderma (diffuse)
anti-mitochondrial
1ry biliary cirrhosis
anti-gliadin
Celiac disease
Anti-basement membrane
Goodpastures
Anti-epithelial
Pemphigus vulgaris
antimicrosomal
Hashimoto's thyroiditis
anti-jo-1
polymyositis, dermatomyositis
HLA B27
Psoriasis, Ankylosing Spondylitis, IBD, Reiters
HLA B8
Grave's, celiac
HLA DR2
Multiple sclerosis, Hay fever, SLE, Goodpastures
HLA DR3
DM type I
HLA DR4
RA, DM type I
HLA DR5
Pernicious Anemia
Hashimoto's
HLA DR7
Nephrotic syndrome
What happens in hyperacute rejection?
Ab mediated- preformed
within minutes
What happens in acute rejection?
Cell mediated from cytotoxic Ts against MHCs.
Weeks after transplant. Cyclosporin and OKT3 prevent
What happens in chronic rejection?
AB-mediated vascular damage- (Fibrinoid necrosis)
months to years
irreversible
What happens in GVHD?
Immunocompetent T-cells proliferate in irradiated immunocomprimised host and rejects host proteins.

Organ dysfunction,
maculopapular rash, jaundice, hepatosplenomegaly, diarrhea.
What happens in Bruton's agammaglobulinemia?
Decreased production of B-cells. X-linked recessive defect in a tyrosine kinase gene associated wtih low levels of all classes of Igs. Recurraent bacterial infections after 6 months of age. Boys
(x-linked)
What happens in DiGeorge syndrome?
Thymic aplasia. Thymus and parathyroids fail to develop-> failure of 3rd and 4th pouch.
Tetany from hypocalcemia. Recurrent viral and fungal infections. Gongenital defects of heart and great vessels

22q11 deletion
What happens in Severe Combined Immunodeficiency?
B and T cell demise
Defect in stem-cell differentiation. Recurrent viral, bacterial, fungal, protozoal infections

Can come from failure to synthesisze MHCII, IL2 receptors, or adenosine deaminase deficiency
What happens in IL-12 receptor deficiency?
Decreased activation of T-cells.
Disseminated mycobacterial infections
What happens in hyper IgM syndrome?
Defect in CD40L on CD4 T helpler cells-> no class switch in Abs.
Severe pyogenic infections
High levels of IgM, no IgG, A, or E
What happens in Wiskott-Aldrich syndrome?
X-linked defect in the ability to mount an IgM response to capsular polysaccharides of bacteria.
Increased A, normal E, low M
Infection
Purpura
Eczema
What happens in Job's Syndrome?
Failure of gama-IFN production by helper T-cells. Neutrophils fail to respond to chemotactic stimuli. Recurrent staph abscesses, eczema, corse facies, retained primary teeth, high levels of IgE
What happens in Leukocyte adhesion deficiency syndrome?
Defect in LFA-1 adhesion proteins on phagocytes. Pyogenic, fungal infections, delayed separation of umbilicus
What happens in Chediak-Higashi disease?
AR
Defect in microtubular function, lysosomal emptying of phagocytic cells. Recurrent pyogenic infections by staph and strep.
partial albinism, peripheral neuropathy
What is chronic granulomatous disease?
Defect in phagocytosis of neutrophils from deficiency of NADPH oxidase. Marked suceptibility to opportunistic infections with S. Aureus, E. coli, Aspergillus. Dx- with negative nitroblue tetrazolium dye reduction test.
What happens in chronic mucocutaneous candidiasis?
T-cell dysfunction against candita albicans.
What happens in selective immunoglobulin deficiency?
Deficiency in a specific class of immunoglobulins.
from defective switching.
IgA is most common.
Sinus and lung infections, milk allergies, diarrhea
What happens in ataxia-telangiectasia?
DNA repair enzymes with associated IgA deficiency. Cerebellar problems, spider angiomas.