DCs and Monos Flashcards
What is the purpose of CD80/CD86 expression on DCs?
Coreceptors for CD28 on T cells. These regulate the threshold for T cell activation.
What cytokines can DCs produce that shape T cell differentiation?
IL-12 (Th1)
IL-23, IL-6, IL1-a (Th17)
TGFB (Treg)
What are the markers and transcription factors for migratory DCs?
These are CCR7+ DCs, expressing the TF Id2, and arise from cDC1s and cDC2s present in tissues that upregulate CCR7 and migrate to the LN.
How to derive monocyte-derived DCs from PBMCs in vitro?
Treat with GM-CSF and IL-4. They are APCs, but we are not sure if they are true DCs.
What is the general progression of DC progenitors?
In the BM: Monocyte DC progenitor (MDP) > Common DC Progenitor (CDP) > Pre-DC. Through signaling of CD135/Flt3
Then, Pre-DC exits BM and enters circulation and seeds tissues and LNs, where the cells undergo further differentiation.
What markers were used to classify different subsets of pre-DCs?
SiglecH and Ly6D.
This led to the realization that pDCs are ontologically distinct from other DC lineages. They express high SiglecH and Ly6D and are unable to process or present antigen to naive T cells. They produce high levels of IFNg.
How can you target a cell population that has a transcription factor shared by other cell types?
If you know where the specific enhancers are that are specific for encoding the transcription factor for that cell, you can delete the cell-specific enhancer for the transcription factor.
Where does cDC2 imprinting occur and with what transcription factor?
cDC2 imprinting happens in the peripheral tissues and involves T-bet.
What are Esam+ cDCs?
cDC2As
What do DCs do in response to TLR3 ligation?
Upregulate costimulatory molecules (CD86), produce IFNa/B, IL-6, TNFa, etc.
What does CLEC9A recognize and which DC subtype expresses it?
Recognizes exposed actin filaments; expressed on cDC1.
What type of T cells do CCR7+ DCs induce primarily?
Tregs (and suppress Th17 in gut)
How do lymphocytes enter and exit secondary lymphoid organs?
Lymphocytes enter through High endothelial venules and exit through efferent lymphatics
DCs and antigen will enter through afferent lymphatics
What are the anatomical sections of the LN, beginning at the outermost part and going inward?
Hilus, subcapsular sinus, cortex, paracortex, medulla
What cells are in the cortex of the LN?
B cell follicles and interfollicular T cells (also fDCs)
What cells are in the paracortex of the LN?
T cells and DCs
What cells are in the medulla of the LN?
Some B cells and plasmacells.
What anatomical region of the LN are the HEVs located?
paracortex, which is mostly T cells and DCs. B cells continue on to the cortex/B cell follicles.
Blood flow through LN
Afferent artery, branched loops into cortex & capillary beds for oxygen exchange, regroup into postcapillary venule, HEV in paracortex, efferent vein.
How do lymphocytes enter the spleen?
passive entry through the marginal zone sinus, no HEV and not regulated. NO lymphatics
What is the area of T cells surrounding the central arteriole in the spleen called?
The Perioarteriolar lymphatic sheath (PALS)
What are the three steps of lymphocyte entry through HEV?
Tethering/rolling
Firm adhesion
transmigration
What are the two molecules that mediate lymphocyte rolling on the HEV?
L-selectin (lymphocyte)
PNAd (endothelium)
What are the two molecules that mediate adhesion and transmigration in the HEV?
LFA-1 (lymphocyte)
ICAM-1 (endothelium)
How would you test (30-40 yrs ago) the hypothesis that cells might interact with HEVs?
take a section of the lymph node including the HEV and place lymphocytes on it. See what sticks, basically.
How if LFA-1 activated on T cells?
engagement of CCR7 by ligands, particularly in the lumen
Where is CCL19 expressed?
Expressed by FRCs, bound to the HEV endothelial cells.
Where is CCL21 expressed?
Expressed and apically displayed on HEVs
What chemokines are required for LFA-1 activation and therefore firm adhesion to the HEV?
CCL21, CCL19
What is the at-large structure of LN?
3D fishing net (collagen fibers/FRCs) with big cords coursing through (blood vessels), filled with packed lymphocytes
Where is the conduit system in LNs?
In the potential space between collagen fibers and surrounding FRCs
How can you study a chemokine that might be important for follicle entry or LN compartment organization if you think it may also be important for LN entry?
Study it in the spleen! No HEV entry, no selection. Blood gets DUMPED in there.
What research tool can be used to inhibit GPCR mediated signaling?
Pertussis toxin (PTX).
This is how they found out about B cell entry into follicle homing.
What assays can you use for chemotaxis testing?
Transwell assays that have a sieve that is too small for lymphocytes to fall through, but big enough for them to squeeze through
How do you study ko mice that are embryonic lethal?
Generate adult hematopoietic “KO” mice by irradiating and making fetal liver chimeras
What are the changes in lymph node architecture in the context of an immune response?
Increased blood flow and remodeling of feeding arteriole
Alterations in HEV expression of chemokines and cell adhesion molecules
Angiogenesis occurs to increase blood supply, portals of entry and deliver oxygen and nutrients
How are lymphocytes retained (decreased exit) in the LN during immune response?
Upregulation of CD69 is inherently linked with downregulation of S1PR on lymphocytes. After 3 days, re-upregulation of S1PR occurs.
What are the three types of interactions that mast cells can undergo?
Direct interactions (TCRs) Fc-receptor-mediated interactions Complement-receptor mediated interactions
How does allergen shuttle work?
cDC2s in the skin continuously sample allergens from the circulation and distribute them via microvesicles to APCs or IgE-coated mast cells, leading to degranulation.
How to culture mast cells in vitro?
IL-3 and stem cell factor (SCF)
What is the gene identified for mast cell and basophil cre-mediated studies?
carboxypeptidase 3 (cpa3)
What are the positional differences between mast cells and basophils?
Mast cells are more in the periphery, while basophils are more circulating.
IL-5
Also known as eotaxin. Recruits eosinophils. Th2 cytokine
What are some pathways through which emergency granulopoiesis is initiated?
Direct recognition of MAMPs via TLRs by HSCs in the BM.
What are the four families of adhesion molecules involved in leukocyte migration?
Selectins, Integrins (heterodimers a + B chains), Immunoglobulin superfamily (ICAM-1, VCAM-1), Mucin-like glycoproteins
Leukocyte Adhesion Deficiency
Rare autosomal disorder characterized by recurrent infections.
3 subtypes (LAD1, -2 or -3)
What are the three subtypes of Leukocyte Adhesion Deficiency (LAD)?
LADI - affects adhesion
LAD II - affects neutrophil rolling (PSGL-1 and selectin interaction)
LAD III - affects neutrophil activation
CD marker makeup of integrins
CD18, paired with CD11a, CD11b, or CD11c
