Immunology (FA+ UW) Flashcards
what does the binding of PD1 (Tcell) to PDL1 cause?
T cell inhibition/exhaustion
PDL1 is often upregulated by cancer cells
loss of thymic shadow+ diarrhea + oral candidiasis + failure to thrive ( or other severe infections)
SCID (loss of both B and T cells)
what types of cells are active during anaphylaxis? what do they release?
- basophils and mast cells
- – tryptase and histamine
explain the process leading to mast/basophil degranulation in anaphylaxis
- surface of mast and basophils have high affinity IgE receptors
- when the mast and basophils encounter large amounts of IgE, their Fc portion of the IgE receptor binds the IgE, and the receptors aggregate!
- – the clumping of the receptors leads to degranulation via a pathway with nonreceptor tyrosine kinases
what are the two types of pneumococcal vax? compare and contrast
- polysaccharide and conjugated
- the polysacch covers more serotypes, but is less “immunogenic”. its not used for kids under 2, because these kiddos lack a robust humoral response
- the conjugated vax is conugated with diptheria protein, and this allows for Tcell recruitment and formation of memory Bcells
Henoch Schonlein Purpura is what kind of HS rxn
Type III
because it is IgA antigen immune complexes
what are the 2 jobs eosinophils do?
- ) antibody-dependent cell mediated toxicity – kill parasites by binding to IgE’s
- ) Type 1 HS— release PGE,Luekotrienes, cytokines in the later phases of Type 1 HS
HIV patients lack
(1) what to prevent superficial Candidiasis
(2) what to prevent disseminated Candidemia
(1) TH1
(2) neutrophils
what marker of Hep B indicates that the infection has resolved
anti- HBs
CD3 is on?
T cells
for signal transduction from the TCR
TCR is on?
T cell to bind antigen-MHC
CD28 in on ?
T cell, to bind B7 on APC (for costim signal)
CXCR4/CCR5 is on?
CD8+ Cytotoxic T cells
its what HIV binds
CD40L is on?
CD4+ T cell, to bind CD40 on Bcell and cause isotype switching
what does the Treg cell have?
CD25, CD4
CD19, CD20, CS21, CD40 is found on?
what other things are alco found on it?
BCell
also: MHCII, and B7 (bc its an APC!), as well as Ig
CD 14 is found on?
what else is found on it?
Macrophages ( it is a receptor for PAMPs)
CD40, CCR5
MHCII, B7
NK cells have what?
CD56
Hematopoietic cells have what?
CD34
what happens when there isnt a co-stimulatory signal (B7- CD28)?
Anergy-a mechanism of self tolerance
B and T cells can experience this
How do superantigens work?
found in s.aureus and s.pyogenes.
they can cross link the Tcell TCR to the Bcell MHCII
causes overactivation of CD4+— resulting in massive cytokine release
how do gram - bacteria get an immune response?
They have endotoxins/LPS that can bind TLR4/CD14 of macrophages (note that T cells are not involved here)
how do intereferon alpha and interferon beta work
they are released by cells infected by the virus.. they go tell their neighboring cells (uninfected) to up their viral defense and get ready to degrade viral nucleic acid and protein
what gives sputum its green color?
myeloperoxidase
a blue green heme containing pigment
How does oxidative/respiratory burst work?
Its first step involves the activation of NADPH oxidase complex.
This gets O2 to become an oxide. From there, SOD and myeloperoxidase make it into HClO radical able to kill bacteria
(note that NADPH also plays a role in neutralizing the radical later)
why are people with CGD at risk for catalase positive infections?
- CGD means no NADPH so no first step of oxidative burst.. BUT bacteria make their own oxygen radicals.. the rest of the steps are intact so the neutrophil/monocyte can use oxide radicals made BY the bacteria to KILL the bacteria
- note that catalase positive bacteria are able to NEUTRALIZE the oxide radicals they make, so now in patients with CGD no respiratory burst can occur
IL1
fever+inflamm
induce chemokine production to recruit WBC
makes endothelin express adhesin
IL2
promotes growth of T cells (helper/cytotoxic/reg) + NK cells
IL3
stimulates the BONE marrow to grow bone marrow stem cells (acts like GCSF)
IL4
IgE isotype swtiching (as well as IgG)
promotes T cells to become TH2
promotes B cell growth
IL5
IgA isotype switching
eosinophil growth
B cell growth
IL 6
promotes creation of “acute phase reactants”– (like CRP ..)
also causes fever
IL 8
chemoattractant for neutrophils
IL12
promotes differentiation to TH1 cells
also activates NK cells
TNFalpha
activates endothelium– WBC recruitment/vascular leak
cachexia
maintain granuloma in TB
who mediates SEPSIS
IL1, IL6, TNFalpha
Interferon y
promotes conversion to TH1/ inhibits TH2 differentiation
secreted by NK and T cells in response to IL12 by macorphages
activates NK and macrophages to kill
where is complement made
liver
what are the three paths of complement production and what’s unique about each?
(1) classic- IgM/IgG mediated— activates C1 first
(2) Alternative- mediated by surface of microbe– activates C3 (terminal complement) first
(3) Lectin (microbe surface that has sugars)- activates C1 like complement first
what is the role of the terminal part of the complement cascade? (aka after C3b is made)
after C3b is made— it makes C5a
– it also makes C5b that is joined by C6-C9to make the MAC
name the two primary opsonins?
IgG and C3b
what do C3a, C4a, and C5a do?
a= anaphylaxis
C5a is also chemoattractant for neutrophil
what is C5b-9
MAC complex
important to lyse gram -
especially important in protecting against Nisseria
what inhibits the complements?
DAC/ CD55
and C1 esterase inhibitor
c3 deficiency can cause?
severe, recurrent pyogenic sinus and respiratory infections
more susceptible to type III HS (bc C3 is what clears the immune complexes!)
C1 esterase inhibitor deficiency
angioedema due to unregulated activation of Kallikrein– causing increased bradykinin (so dont use ACEi duhh)
CD55 defieciency
PNH.. can cause complement mediated destruction of RBC
what are acute phase reactants?
remember they are mediated by IL6
they are factors whose serum concentrations change during inflammation :
CRP, Ferritin, Fibrinogen, Hepcidin, serum Amyloid A, Albumin, Transferrin
what do mature but NAIVE B cells have as surface Ig’s
IgM
IgD
whats the most abundant Ig isotype in serum? what’s it do?
IgG!
- main antibody in secondary (delayed response)
- DOES cross placenta
- fixes complement, opsonizes bacteria
what does IgA do?
prevents attachment of foreign bodies to mucosal membranes (Giardia)
released in secretions like breast milk, saliva, tears
produced the most, but has low serum concentration
does not fix complement
what does IgM do?
- primary (immediate) response
- doesnt cross placenta
- pentamer so has avid binding abilities
- fixes complement