Immunology Flashcards
Medulla of lymph node
Medullary cords with closely packed lymphocytes and plasma cells
Medullary sinuses
Contain reticular cells and macros communicate with efferent lymphatics.
paracortex
Houses T cells. Between cortex between follicles and medulla. High endothelial venules
Which part of lymph node enlarged in immune response?
paracortex. This part is also underdeveloped in digeorge syndrome
stomach drains to
celiac node
duodenum drains to
superior mesenteric node
sigmoid colon drains to
colic then inferior mesenteric
rectum drains to
internal iliac nodes
anal canal below pectinate drains to
superficial inguinal
testes drain to
superficial and paraaortic
scrotum drains
superficial inguinal node
thigh drains
superficial inguinal node
lateral dorsum of foot drains
popliteal
right lymphatic duct drains
right arm, right chest, right half of head
thoracic duct drains
everything beisdes what the right lymphatic duct drains
structure of sinusoids of spleen
vascular channels in red pulp with barrel hoop basement membrane
T cells of spleen found in
periarterial lymphatic sheath in white pulp
B cells of spleen found in
follicles on outer edge of white pulp
Macrophages of spleen are especially important for
removing encapsulated bacteria
What are the encapsulated organisms?
Strep HiB Neisseria Salmonella Klebsiella Group B
Findings in a blood smear after a splenectomy
howell jolly bodies
target cells
thrombocytosis
Cortex of thymus
immature T cells
medulla of thymus
pale with mature T cells
epithelial reticular cells coming together to make hassall’s corpuscles
positive selection (MHC restriction) occurs
in the cortex of thymus
negative selection (nonreactive to self) occurs
in the medulla of thymus
MHC I is expressed on all nucleated cells except for
RBCs
B2 microglobulin
part of MHC1, helps to transport molecule to cell surface
loading of antigen in MHC II
release of invariant chain in acidified endosome
loading of antigen in MHC1
in RER with intracellular peptides
HLA A3
hemochromatosis
HLA DQ2/DQ8
celiac
HLA DR2
multiple sclerosis
SLE
Goodpasteur’s
HLA DR3
Graves’ Diabetes type 1
HLA DR4
rheumatoid arthritis, diabetes type 1
HLA DR5
pernicious anemia
Hashimoto’s thyroiditis
when do NK cells kill?
Exposed to a nonspecific activation signal on target or absence of class I MHC
NK activity enhanced by
IL-2, IL-12, IFN beta, IFN a
When an immature T cell enters the thymus, it immediate gets what receptors?
CD4+ CD8+ AND TCR
SIgnal for Helper T cells to become Th1 cells
IL-12
Signal for helper T cells to become Th2 cells
IL-4
Positive selection
T Cells expressing TCRs able to bind self MHC survive
negative selection
T cells expressing TCRs with a high affinity for self antigens= apop
costimulatory signal
B7 expressed by DC
CD28 expressed by naive T cell
What happens after the primary and costimulatory signal is given by dendritic cell to naive T cell?
Naive T cell expresses IL-2 which binds to IL-2R on itself stimulating the naive T cell to differentiate
What happens after the primary and costimulatory signal is given by Th4 cell to naive B cell?
the helper T cell, after being activated by dendritic cell
- ->B cell presents antigen on MHC II to activated T cell
- ->TCR recognizes correct antigen and releases IL4 and IL5 which stimulate the B cell to differentiate into IgG, IgE, and IgA
What is the only APC that can activate a naive T cell?
the dendritic cell
Describe the costimulatory signal for B cell activation
CD 40 on B cell
CD40 L on Th cell
Th1 cell secretes
IFN-y
Th2 cell secretes
IL4, 5, 10, 13
Th1 cell activates
macrophages
Th2 cell activates
Eosinophils
IgE production by B cells
Th1 cell inhibited by
IL4 and IL10
Th2 inhibited by
IFN-y
How do macrophages and lymphocytes tickle or stimulate each other?
lymphocytes release IFN-y
macrophages release IL1 and TNF-a
–> they help each other out
Hyper IgM caused by
Defective CD 40 and 40L interaction
Contents of cytotoxic T cells (CD8)
granules with
- perforin: makes holes so can deliver bombs
- granzyme: serine protease, activates apoptosis
- granulysin: antimicrobial, induces apoptosis
Treg cells express which cell surface markers
CD3, CD4, and CD25
Treg cells produce
IL10 and TGFbeta
heavy chain makes up which portions of antibody
Fc and Fab
light chain makes up which portion of antibody
Fab
CD25 is also known as
alpha chain of IL-2 receptor.
complement binds which part of antibody
medial portion of Fc
macrophage binds which part of antibody
distal to where complement binds, between CH2 and CH3
three components of the Fc region
carboxyterminal end
complement binding at CH2 (IgG and IgM)
Carbohydrage side chains
light chains made up of
VJ
heavy chains made up of
VDJ
stomatic hypermutation occurs after
antigen stimulation of B cell. BUT B cells are “born” with their random VJ/VDJ combinations.
What enzyme is responsible for generating the VD/VDJ recomination?
terminal deoxynucleotidyl transferase
–Adds nucleotides to DNA during recombination
isotype switching
When B cells secrete things other than IgM
Mature B lymphocytes express what on their surface
IgM AND IgD
Which antibody can cross the placenta?
IgG
Which antibodies can fix complement?
Only IgG and IgM
which antibody is responsible for delayed response to an antigen?
IgG
How does IgA work?
Prevents attachment of bacteria to mucous membranes
IgA form in circulation?
monomer. dimer when secreted
Which Ig is the antigen receptor of the surface of B cells?
IgM
thymus independent antigens
antigens lack a peptide component and cannot be presented by MHC to T cells (ex: LPS or capsular antigen)
- ->as a result, NO immunologic memory
- ->but antibodies are released
Thymus dependent antigens
There IS a protein component (diptheria) and class switching occurs
Classic complement pathway
IgG or IgM mediated
Lectin pathway
mediated by Mannose on microbe
Alternative pathway turned on by
PAMP pathogen associated molecular pattern
C3b
opsonization
C5a
neutrophil chemotaxis
What starts the alternative pathway?
C3–>C3b
AND
D converts B into Bb
=C3bBb
what starts the lectin pathway?
MBL activates a C1 like complex
- -cleaves C2 AND C4
- -otherwise, same as classic pathway
primary opsonins
IgG
C3b
What prevents complement activation on self cells?
Decay accelerating factor
C1 esterase inhibitor
complement disorder with hereditary angioedema
C1 esterase inhibitor deficiency
What drug is contraindicated in C1 esterase inhibitor deficiency?
ACE inhibitors
severe pyogenic sinus and respiratory tract infections with increased type III hypersensitivity–type of complement deficiency
C3 deficiency. C3 helps clear immune complexes
Recurrent neisseria bacteremia
C5-9 deficiency
Complement mediated lysis of RBCs and PNH
DAF deficiency
What does IL-1 do to endothelium?
induces adhesion molecule expression
IL6
fever and acute phase proteins
IL8
neutrophil chemotaxis
IL12
Differentiation into Th1 cells
Activates NK cells
IFN-y
Increase MHC I and II expression.
Interferon a and b mechanism
Produce a ribonuclease=degradation of viral mRNA
IFN is defense against
VIRUSES
–they all activate NK cells to kill virus infected cells
Cell surface proteins on T cells
TCR
CD3
CD28
CD proteins on Th4
CD4, CD40L
B cell CD proteins
CD19, 20, 21
40, MHCII, B7
Receptor for epstein barr virus
CD21
Macrophage receptors
CD14 (binds LPS)
CD40
MHC II
B7
NK cell receptors
CD16 (binds Fc)
CD56 (unique marker)
Superantigens secreted by which bugs?
S aureus (TSST-1) S pyogenes (exotoxin A) -->NOTE THAT ALL T CELLS ARE ACTIVATED from cross linking fo TCR to MHC II on APCs
LPS stimulates
macrophages!
Thelper cells are NOT involved. Massive secretion of TNF alpha
Salmonella antigen variation
flagella
neisseria gonorrhea antigen variation
pilus protein
what other bugs have antigen variation?
trypanosomes
borrelia
When do you give passive immunization?
Tetanus
Botox
Rabies
HBV
Live vaccines activate a
cellular response
killed vaccines activate a
humoral immunity
examples of killed vaccines
Rabies Influenza (shot) Polio (salk) HAv Cholera
marker of mast cell degranulation
tryptase
Explain Type II hypersensitivity
IgM/G bind to antigen
- -opsonization
- -complement lysis
- -Antibody dependent cell mediated cytotoxicity, NK cells
How to test for type II hypersen
Direct and indirect coombs’
serum sickness
immune complex disease where immune complexes bind and deposit where they fix complement=tissue damage
arthus rxn
Intradermal injection induces antibodies and complexes in the skin.
—edema, necrosis, activation of complement
When would you see serum sickness?
5-10 days after exposure
most serum sickness is caused by
drugs
Sx: serum sickness
fever, urticaria, arthralgias, protienuria, lymphadenopathy
Test for arthus rxn
immunofluorescen staining
Describe process of type IV hypersensitivity
t lymphocytes activate macrophages and secrete lymphokines
Examples of type IV hypersensitivity
multiple sclerosis guillain barre graft versus host disease contact dermatitis tranplant TB skin test
allergic rhinitis and hay fever
Type I hypersensitivity
Four types of blood transfusion reactions
allergic rxn
anaphylactic
febrile nonhemolytic
acute hemolytic transfusion
concern when giving blood transfusion to pt with celiac’s
many celiac’s pts are deficient in IgA
–must receive blood products that lack IgA
Febrile nonhemolytic transfusion rxn
type II hypersensitivity. Host antibodies against donor HLA antigens
sx of febrile nonhemolytic TR
fever, chills, flushing
Acute hemolytic transfusion rxn
type II hypersensitivity. Intravascular hemolysis or extravascular hemolysis
Sx of acute hemolytic transfusion rxn
fever, hemoglobinemia, jaundice (extravascular)
flank pain, hypotension
Anti-histone antibody
Drug induced lupus
anticentromere
CREST
antiScl70 (DNA topo I)
Diffuse scleroderma
antimitochondrial
primary biliary cirrhosis
IgA antiendomyseal
celiac
anti-desmoglein
pemphigus vulgaris
antimicrosomal
hashimotos
also antithyroglobulin
Anti Jo-1, Anti-SRP, Anti-Mi2
polymyositis
dermatomyositis
Anti-SSA/SSB
sjogren
anti-smooth muscle
autoimmune hep
anti glutamate decarboxylase
t1D
p-ANCA
microscopic polyangiitis, churg strauss
c-ANCA
granulomatosis with polyangiitis
anti-glutamate decarb
type 1 diabetes
anti-U1 RNP
mixed CT disease
No B cells: susceptible to which bacteria?
Encapsulated
No complement: susceptible to which bacteria?
Neisseria
No granulocyte: susceptible to which bacteria?
Staph
Serratia
Nocardia
No T cells: susceptible to what bacteria?
everything. Sepsis!
No T cells, susceptible to which viruses?
CMV
EBV
VZV
how do you test for type IV hypersensitivity?
candida extract skin test
Does the absence of anti-dsDNA of anti-Smith rule out possibility of SLE?
NO–these are highly specific for ruling in
recurrent Candida
PCP
No T cells
Recurrent giardia infection
No B cells (no IgA)
Recurrent candida and aspergillus
No granulocytes
recurrent bacterial infections 6 months after birth
- normal proB
- low B cells
- low Ig (all types)
Bruton’s X linked agammaglobulinemia
Cause of bruton’ x linked agamma?
Defect in Bruton tyrosine kinase so NO B CELL MATURATION
asymptomatic but recurrent sinopulmonary/GI infections. Also history of celiacs or other autoimmune.
Selective IgA deficiency.
what do pts with selective IgA deficiency test false positive for?
beta HcG. cuz of heterophile antibody
what is a heterophile antibody?
induced antibody that is characterized by broad reactivity with antibodies of other animal species
pt in 20’s and 30s suddenly present with lymphoma and sinupulmonary infections. Normal B cell number but decreased plasma cells and immunoglobulin
CVID
Cause of CVID
defect in B cell maturation
pts with CVID increased risk of
autoimmune dz
pt has tetany, recurrent viral/fungal infections
DiGeorge syndrome
lab findings in Digeorge
absent thymic shadow
- -low PTH
- -low T cells
- -low calcium
cause of DiGeorge
22q11 =failure of 3rd and 4th branchial pouches to form
also cause of tetraology of fallot and persistent truncus arteriosus! cool!
disseminated mycobacterial infections
IL-12 receptor deficiency
lab findings in IL12 receptor deficiency
decreased IFN-y
coarse facies
staphylococcal absecess
primary teeth retained
Eczema
Hyper IgE (Job’s syndrome)
Cause of hyper IgE (Job’s)
Th1 cells fail to produce IFN-y
- -neutrophils fail to go where they need to go
- -will have lots of Th2 cells
candida infections of skin and mucous membranes
Chronic mucocutaneous candidiasis
–caused by T cell dysfunction
Failure to thrive, chronic diarrhea
–recurrent fungal, viral, bacterial infections
SCID
XRay and lymph node biopsy findings in SCID
Absence of thymic shadow No germinal centers in lymph nodes No B cells --Decreased Tcell recombinant excision circles --decreased T cells on flow cytometry
cause of SCID
- Defective IL2 (most common)
2. Adenosine deaminase deficiency
Ataxia, spider angiomas, and IgA deficiency
ataxia telangiectasia
Cause of ataxia telangiectasia
Defects in ATM gene: codes for DNA repair enzymes
Lab findings in Ataxia telangiectasia
Increased AFP
Severe pyogenic infections early in life
Hyper IgM
Cause of hyperIgM
defective CD40L cannot class switch
thrombocytopenic purpura
infections
eczema
wiskott aldrich syndrome
Cause of wiskott aldrich
WAS gene defective. T cells unable to reorganize actin cytoskeleton
inheritance of wiskott aldrich
X linked
Lab findings of wiskott aldrich
Increased IgE, IgA
Decreased IgM
Low platelets
Recurrent bacterial infections, no pus, and delayed separation of umbilical cord
leukocyte adhesion deficiency
Cause of Leukocyte adhesion deficiency
Defect in LFA-1 integrin (CD-18)
lab findings in leukocyte adhesion deficiency
neutrophilia
recurrent pyogenic infections by staph and strep
PARTIAL albinism and peripheral neuropathy
chediak higashi
Cause of chediak higashi
Defect in lysosomal trafficking regulator gene (LYST). Microtubule dysfunction in phagosome-lysosome fusion
inheritance of chediak higashi
Autosomal recessive
giant granules in neutrophils
lab findings in chediak higashi
abnormal dihydrorhodamine flow cytometry test
chronic granulomatous disease
susceptibility to catalase positive organisms (S aureus, E coli, aspergillus)
chronic granulomatous disease
cause: Chronic granulomatous disease
lack of NADPH oxidase. Cannot make reactive oxygen species in neutrophils
Susceptible to BOTh catalase positive and negative orgs
myeloperoxidase deficiency. Cannot turn H2O2 into an O2 radical…EVEN though H2O2 is provided by catalase negative organisms!
syngeneic graft
From identical twin
acute rejection time frame
weeks
chronic rejection time frame
months to years
hyper acute rejection: type of hypersensitivity rxn?
Type II. preformed antibodies in transplant recipient attack donor cells (blood mismatch)
occlusion of graft vessels causing ischemia and necrosis
hyperacute rejection
vasculitis of graft vessels with dense intertitial lymphocytic infiltrate
acute rejection
Fibrosis of graft tissue and blood vessels
chronic rejection.
mechanism of acute rejection
Cell mediated
- CTL react against foreign MHC
- Reversible
which rejection is NOT reversible?
chronic
macropapular rash, jaundice, hepatosplenomegaly and diarrhea in a transplant pt
GVH disease
which types of transplants most susceptible to GVH disease?
bone marrow and liver transplants (rich in lymphocytes)
Mech: cyclosporin
blocks diff and activation of T cells
- -inhibits calcineurin.
- -No IL2 and IL2R
tox of cyclosporine
nephrotoxicity hypertension hyperlipidemia/glycemia gingival hyperplasia hirsutism
Mech: tacrolimus
Binds FK binding protein, inhibiting calcineurin
tox of tacrolimus (FK506)
same as cyclosporin, but NO gingival hyperplasia and NO hirsuitism
Sirolimus (rapamycin) mechanism
Inhibits mTOR and T cell proliferation
Use of sirolimus
tranplant and drug eluting stent
toxicity: sirolimus
hyperlipidemia, thrombocytopenia, leukopenia
mechanism: azathioprine
precursor of 6 MP
- -interferes with synthesis of nucleic acids
- -toxic to lymphocytes
Use azathioprine
kidney transplant
–GN and hemolytic anemia
Muromonab-CD3 (OKT3) mech
Binds CD3 and blocks T cell signal
Tox of muromonab
cytokine release syndrome, hypersensitivity
use: muromonab
kidney transplant
Omalizumab
Anti-IgE for sever asthma
aldesleukin
IL-2
Use: aldesleukin
RCC
metastatic melanoma
EPO
renal failure anemia
filgrastim
GCSF
sargramostim
GMCSF
alpha IFN use:
Hep B, C
kaposi’s
leukemia
malignant melanoma
B IFN
multiple sclerosis
y interferon
chronic granulomatous disease
Oprelvekin
thrombocytopenia
Use: filgrastim/sargramostim:
Recovery of bone marrow
trastuzumab
HER 2 antibody
Describe the process of inflammatory leukocyte migration
- margination
- rolling: with sialyl acid binding to L, E or P selectin (induced by cytokines)
- activation of integrins
- MAC-1 and LFA-1 integrins bind ICAM-1 on leukocyte
- transmigration