Study your flashcards anywhere!

Download the official Cram app for free >

  • Shuffle
    Toggle On
    Toggle Off
  • Alphabetize
    Toggle On
    Toggle Off
  • Front First
    Toggle On
    Toggle Off
  • Both Sides
    Toggle On
    Toggle Off
  • Read
    Toggle On
    Toggle Off

How to study your flashcards.

Right/Left arrow keys: Navigate between flashcards.right arrow keyleft arrow key

Up/Down arrow keys: Flip the card between the front and back.down keyup key

H key: Show hint (3rd side).h key

A key: Read text to speech.a key


Play button


Play button




Click to flip

93 Cards in this Set

  • Front
  • Back
Name two different types of dendritic cells?

What are their functions?
Interdigitating (activates T cells in lymph node via MHC) AND Follicular (helps mature B cells - does not have MHC).
Interdigitating cells are found in....

Follicular cells are found in...
Present in most organs (they migrate to lymph node and activate T cells in the paracortex region)

Lymph node and spleen
Addressins are found....
on HEVs of secondary lymphoid tissues and inflammed endothelium.
Last stage of immune response....

For Extracellular Pathogens

For Intracellular Pathogens
For Extracellular Pathogens -- (1) CD4-Th1 -> Activate macrophage to kill pathogens (2) Ab molecules bind to pathogens and activate complement system for their destruction

For Intracellular Pathogens
(1) CD8-Cytotoxic T cells -> Kill the host cell via perforin and granzyme enzymes
(2) NK Cells
Which enzymes are released by Cytotoxic T cells?
Perforin and Granzyme
How is the mode of action different for Helper and Cytotoxic T cells?
Helper T cells - Activate Macrophage. Use MHCII to recognize Ag.

Cytotoxic T Cells - Kill host cell directly and recognize Ag via MHCI.
Which organ is important for systemic infection?
Spleen - it removes damaged RBCs.
List the cells that come from lymphoid lineage and erythroid lineage?
Lymphoid...T cells, B cells and NK cells

Erythroid - RBC, Megakaryocytes (Platelets)
List the cells that are from myeloid lineage and where are they found?
Neutrophil (blood)
Basophil (blood)
Eosinophil (blood)
Mast Cells (tissues, CT)
Macrophages (tissues, CT)
Dendritic cells (tissues, CT)
List three unique characteristics of NK cells?
(1) Do not have TCR or product Ig.
(2) Secrete IFNy
(3) Destroy cells with intracellular pathogen (just like cytotoxic T cells)
Which granylocytes are....

Attach to IgE?
Release histamine?

Eosinophil, Basophil (and Mast cells)

Basophil (and mast cells)
Which cells are primary players in allergic response?
Mast cells (also involved are Basophils, Eosinophils)
Which cells are considered to be circulating counterpart of Mast cells?


because they both bind to IgE and release histamine as part of the allergic response.
List the APC for innate and acquired immune response.
Innate - Macrophages

Acquired - Macrophages, Dendritic (Interdigitating and Follicular)
List the two types of Dendritic cells?

Where are they found?

Their function and What kind of receptor are found on their surface?
Interdigitating - in most organs. Pick up Ag, travel to lymph node and present Ag to T cells via MHC II (in the paracortex of the lymph node).

Follicular - In follicles of lymph node and spleen. Present Ag to B cells (do not have MHC II, instead have Fc receptors to trap Ag:Ab complement).
Name the specialized epithelial cells that deliver pathogens across mucosa?
M cells
What is the structure of integrin?

What is their function?
heterodimeric molecules consist of alpha and beta chain.

Leukocyte adhesion to endothelium or other immune cells.
What is the function of following integrin types? Examples?

B1 - Binding cells to extracellular matrix (VLA1-6)

B2 - Leukocyte to endothelium (LFA1, CR3, CR4)

B3 - Interactions of platlets and neutrophils at inflammatory site or sites of vascular damage
What is the function of Addresin?
Bind to circulating T cells at HEVs and direct them to lymphoid tissues.

Help direct T cells to various locations (distinct adhesion molecules on HEVs of different tissues).
Strongest Immunogen
Protein > Polysaccharides > Lipids > Nucleic acids
A substance that nonspecifically enhances the immune response to an Antigen
What are Haptens? Give an example.
Small molecules that do not provoke antibodies by themselves; covalent attachment to a protein carrier makes these molecules immunogenic.

Poison Ivy Catechol
Ig splits...

Papain vs. Pepsin
Papain - yields two Fab and one Fc fragments.

Pepsin - yields 1 Fab' (containing two Ag binding site) and degrades Fc region.
Which Ig...

Crosses placenta?
Is first one to be produced?
Has secretory component?
Marker for naive, mature B cells?
Present at highest levels in serum?
How do Abs work?
(1) Neutralization - Tightly bind to pathogen; inhibiting growth, replication etc..

(2) Opsonization - Phagocytosis of a pathogen when coated with IgG or complement. (Macrophages phagocytosed a pathogen MUCH more efficiently when it is bound to Ab or complement).
Which Ab are good for...

Activation of complement system?
Binding to Mast cells?
Opsonization - IgG

Complement System - IgG and IgM

Neutralization - IgG, IgM

Mast Cell Binding - IgE
List the ways Ab changes after exposure to Ag?
(1) Differential RNA Splicing - (secreted versus membrane bound Ab)

(2) Isotype switching - Heavy Chain Class switching

(3) Hypermutation (increase affinity)
Which cell in B-cell development first shows surface Ig?
Pre-B cell (It has BCR and surrogate light chain)
Which cells express MHC Class I and Class II molecules?
MHC I - All cell except RBC
MHC II - APC; Macrophages, B cells and Dendritic cells and endothelial cells can be induced to express Class II
How are proteins transported from cytosol into the ER?
Using TAP (its gene is contained within MHC gene)
How does Ag get loaded onto Class I?
(1) Calnexin stabilizes ClassI heavy chain until B2m binds.
(2) Calnexin is released as B2m binds.
(3) ClassI heterodimer, Tapasin and Calreticulin bind to TAP. (UNTIL Ag binds)
(4) Ag is transported into ER by TAP.
(5) Ag is presented and ClassI molecule dissociates from Calreticulin, Tapasin and TAP.
What is CLIP?
Fragmented invariant chain on the HLA-ClassII. Invariant chain is digested in the exocytic vesicle and CLIP is what's left on the HLA-II complex.
How is CLIP released from HLAII complex?
MHC like protein that presents lipids.

CD1a-c - Presents to CD4/CD8 T cells

CD1d - Presents to NK cells
List three differences between Ig and TCR?
Ig has (1) Affinity maturation (2) Subtype switching (3) Membrane bound and secreted
Two types of TCR are...
alpha/beta and gamma/delta

(T cells contain one or other but NOT both)
gamma/delta TCR is found in...
mucosal tissues
Variable region of TCR is encoded by which gene (for alpha and beta chain)

Compare this to Ig.
Alpha variable chain - VJ
Beta variable chain - VDJ

(Constant region is Ca, Cb, Cd, Cg)

Ig - Variable heavy chain - VDJ; variable light chain is VJ
How does TCR commit to gamma/delta?
gamma/delta TCR signals Tcell to cease gene rearragement and so TCR remains as gamma/delta.
How does TCR commit to alpha/beta receptor?
If beta chain rearranges before gamma/delta it stops rearragement and forms Pre-TCR (beta chain with surrogate alpha chain). Proliferation begins. Then, gene rearranges to get alpha chain (and delta is deleted).
What is Pre-TCR?
Beta chain with surrogate alpha chain. (Proliferation and alpha chain rearrangement follows)
Which molecule is responsible for signal transduction for TCR?
CD3 (TCR can't leave the surface).

CD3 has intracellular domain with ITAMS.
Which are peptide binding regions in MHC I and MHC II?
MHC I - alpha1 and alpha 2

MHC II - alpha 1 and beta 1
What is superantigen?
A molecule that binds to external portion of MHC and activates TCR without an antigen on the MHC.
Which CD markers are present on T cell during beta chain rearrangement?
CD25 and CD44low
When the a double negative Tcell become double positive T cell? What does double negative mean?
Double negative means CD4-, CD8-.

After beta chain is generated and transferred to the surface (PRE-T CELL stage), T cell becomes double positive.
What is unique about gamma/delta T cells?
(1) They are usually found around mucosal surfaces.
(2) They do not undergo positive or negative selection.
How does dbl-positive Tcell get to be single positive (CD4 or CD8)?
During positive selection, if TCR recognizes MHC I, it becomes CD8+ cell and if it recognizes MHC II, it becomes CD4+ cell.
List three exit markers on the HEV in the lymph node? Which molecule on T cell binds these markers?
GlyCAM1, MadCAM1, CD34

L-Selectin binds these markers to exit endothelial cells.
Which molecules are involved in holding Tcell close to the APC during the screening process?
Which molecules are responsible for co-stimulation during the activation of naive T cell?
CD28 (on T cell) and B7 (on APC)
List the following for T cells...

Coreceptors molecules
Co-stimulatory molecules
Signal transduction molecule
Coreceptors molecules - CD4/CD8
Co-stimulatory molecules-CD28
Signal transduction molecule-CD3
Signaling cascade for T cell.
(1) MHC-Ag-TCR complex binding leads to ITAM phosphorylation.
(2) CD4/CD8 co-receptors binds to stabilize the connection
(3) ZAP70 binds to ITAM
(4) Lck phosphorylates and activates ZAP70
Activated ZAP70 activates...
PLCy -> DAG/IP3 formation -> IP3 activates Calcineurin leading to NFAT activation. AND DAG+Ca activate PKC activating NF-kB.

ZAP 70 also activates GEF -> Induction of MAP kinase -> Fos and Jun induction and AP-1 formation and activation.

Leads to gene transcription.
What is unique about naive CD8 T cell activation?
It requires stronger signal. Only DC can provide this signal by themselves.

Macrophages required IL2 from CD4 to have higher expression of B7 to bind to CD8 T cells.
What are the homing receptor in on T cells for lymphoid organs versus activated endothelium?
Lymphoid Organ - L-selectin
Activated (inflammed) endothelium - VLA4

(these molecules are on the T cells)
Product of splicing of CD45RA.

Associates with CD4 and TCR. Resulting in increased sensitivity to stimulation thus requiring lower concentraion of MHC:Peptide molecules.
Mechanism of action of Cytotoxic T cell.
(1) Release of cytotoxins - Perforin (creates pores) and Granzyme B (enters through pores and cleaves proteins)

(2) FasL on T cell binds to Fas receptor resulting in capsase activation and apoptosis.
Which molecules are important in Th1 differentiation?
IL27, IL12, STAT4 (phosphorylated), T-bet transcription factor
Which molecules are important in Th1 differentiation?
IL27, IL12, STAT4 (phosphorylated), T-bet transcription factor
Mechanism of action of Th1 cell.
Th1 activates macrophages via CD40L and IFNy.

(1) Increase phagocytosis
(2) Synthesizes microbicidal molecules
(3) Increase B7 expression
Which molecule is vital for Th2 differentiation
IL4, Transcription factor GATA3 and STAT6
Which ILs are produced by effector TH2?
IL4 - B cell proliferation
IL5, IL6 - B cell differentiation
Essential for developemtn/fucntion of Tregs.
Function of Tregs?
Involved in peripheral tolerance, prevention of autoimmunity.
Treg is highly dependent on which IL?

Treg produces...

Signal transducers for Bcell and T cell?
B cell - Iga and Igb
T cell - CD3
Coreceptors for Bcell and Tcell?
B cell - CD21, CD81, CD19

T cell - CD4, CD8
What type of Ig are produced by TI Antigens? What are some other characteristics of TI Antigens?
IgM; No class switching, No affinity maturation, No immunological memory
What are signals 1 and 2 for the primary response of B cel activation for TD Ag?
Signal 1 - Ag binding to B cell

Signal 2 - CD40-CD40L contact and cytokines released by CD4 T cell.
List the steps of primary response of B cell immunity.
(1) Ag recognition/binding via BCR (signal 1)
(2) Interaction with Ag specific Th2 (signal 2) driving proliferation/ differentiation
(3) IgM secretion
(4) Some migrate to GC undergo isotype switching, affinity maturation, competition for interaction with Th2s
(5) More proliferation/differentiation(6) non IgM secreting plasma cells and/or memory cells
What are the differences between the primary and secondary response of B cell immunity?
Time course - Secondary is much faster.

Ab titer - Many more Ab produced as part of secondary response

Ab class - Primary is mainly IgM, secondary can be any class.

Ab affinity - Abs produced as part of secondary Ig have higher affinity.
List three important Fc receptors? Their function?
FcyRI - Low affinity, Enhances neutrophil, macrophage ability to phagocytose

FcyRIII - Factilitates cytotoxicity by NK cells via binding to IgG.

FceRI - High affinity receptor, Binds to IgE, Found on mast cells, Basophils and Eosiniphils.
Which receptor is involved in the transcytosis of IgA?
poly-Ig receptor. (It is cleaved in the endocytic vesicle. Fragment that stays with IgA is the secretory component)
Which receptor is involved in the transcytosis of IgG?
Two Brambell receptor (FcRB)
What is passive immunity? Its characteristics
Passive immunity is when Ab from one individual is transferred into another individual. (Mom to fetus)

No immunologic memory is involved with passive immunity.
Intermediate in Completement cascades. This is where all three pathways merge.

C3b on a pathogen marks the pathogen for destruction.
What are the components of C3 convertase and C5 convertase?
C3 convertase - C4b and C2a (C4b2a)

C5 convertase - C4b, C2a, C3b (C4b2a3b)
Steps of classical complement cascase...
(1) C1q binds to IgM or IgG(2)
(2)C1r activates C1s
(3)C1s cleaves C4 and C2
(4)C4b and C2a come together forming C3 convertase
(5) C3b is formed and it binds to the pathogen surface marking it for destruction. (It MUST bind to the pathogen)
What is analogous to C1r and C1s in the Lectin based completement cascade pathway
MASP - Manose associated serine protease (it cleaves C4 and C2)
In the alternative pathway, C3 is cleaved twice; which molecules are used for this cleavage? When does the cleavage happen?
Cleavage 1 - During activation - iC3Bb is soluble and not pathogen bound. (hence it is not called C3 convertase).

Cleavage 2- Via C3 convertase (c3bBb). This happens after C3b has bound to pathogen and properdin has stabilized C3 convertase.
Stabilizes Alt C3 convertase to allow for large deposition of C3b on pathogen surface.
What is C5 convertase in the Alternative pathway
What is produced by NK cells when they recognize mycobacterial lipid?
IL-4 and IFNy
Responsible for maintaining Mono. Proteosome unable to degrade EBNA-1 for presentation to CD8s.
What is DAF?
Decay Accelerating factor - Dissociates C3b and Bb.

Stops complement cascade
How does CR2 inhibit completement cascase?
Dissociates C3b from Bb.
What is MCP? And how does it regulate complement cascades?
MCP - Membrane Cofactor protein.

Works three ways...(1) Dissociates C3b from Bb (2)Cofactor for Factor I (which inactivates C3b by cleaving it) (3) Binds to C4b, making it susceptible to attack from Factor I.
What are HRF and CD59? Mechanism of action?
Inhibit Membrane Attack complex.

Bind to C5b6-8 and prevent C9 polymerization
How are immune complexes removed? (not bound to pathogen)
Complement components C4b and C3b bind to CR1 on RBC, which carries it to spleen for removal.

(Note: When pathogen is bound....opsoniazation, activation of MAC, Inflammation remove pathogen).
What is factor I?
It stops complement pathway by inactivating C3b.
Give an example of an organism that exploits split tolerance?
Mycobacterium Leprae
List the three chemokines that play a role inflammation response?
CXCL8 (IL8) - Chemoattractant for neutrophils

MIP1 (CCL3) - Chemoattractant for CD8

RANTES (CCL5) - Chemoattractant for memory T cells and monocytes etc.. Binds HIV coreceptor.