Immunology Pathway Flashcards
Immune surveillance of an organ
a) Requires lymph nodes
b) Is where soluble antigen travels by efferent lymphatics
c) Antigen is carried in lymph or by DC
d) None of the above
- Lymphatics enable the movement of antigens and cells from the site of entry to the draining lymph node.
- DC conduct surveillance of the tissue. If activated by PAMPs/DAMPs, they migrate towards afferent lymphatics (T-cell zones) to present antigen by MHC1 and 2, and activate CD8 and CD4 T cells.
- Answer c.
Naïve T-cells are:
- Activated by floating antigens
- Activated by tissue-resident macrophages
- Activated by DC in non-lymphoid tissues
- Activated by DC in lymphoid organs
Naive T cells are activated by DC in lymphoid tissues.
DC activated by PAMPs/DAMP. DC are professional APC, uptake antigen and migrate to the AFFERENT LYMPHATICS. Presentation in the LYMPH NODE activated adaptive immune responses.
Activation of naïve CD4+ T-cells can produce different types of T-cells by:
1) Three signals, through the TCR, co stimulation, cytokines
2) only the TCR
3) only the CDR3
4) Cytotoxic “Killer” T-cells
CD4+ T cell activation needs
- signal 1 (antigen-specific stimulation - antigen peptide/MHC complex),
-signal 2 (costimulation - CD28 or CD80),
-signal 3 (polarization - cytokines, membrane-bound molecules).
Answer 1.
True or False:
Cytotoxic T-cells destroy target cells by releasing cytokines.
True.
Cytotoxic releases granzymes and perforin to kill target cells that they bound to. They are not cytokines. They are proteins.
A bacterial pathogen that was encountered for the first time has been eliminated by the immune system. What is most likely happening in the immune response at this time?
a) There is an abundance of bacterially derived epitopes and T-cells are expanding
b) There is less pathogen so less antigen, reduced numbers of antigen specific T-cells
c) Memory T-cells are produced
d) B and C
e) None of the above
Once recovered, memory cells produced. Number of activated lymphocytes (B and T cells) also reduced.
So, d.
True or False:
ELISPOT assays would be just as effective using purified T-cells, without antigen presenting cells.
Whole blood from patients contain APC, CD4+, CD8+ T cells. Antigen is added to cells. Antigen got phagocytosed by APC, presented to T cells by MHC2. Plate is coated with antibodies that bind IFN gamma (cytokines secreted by activated T cells). Detection antibody and substrate addition is added to make spots visible.
So, false.
Memory CD8 T cells
a) Do not exist, only CD4 T cells form memory cells
b) Can enter tissue and kill virus-infected target cells without co-stimulation.
c) Reside in the spleen until activated to respond to a challenge infection.
d) Are the main outcome of most protein-based vaccinations.
- b!
- ## Both CD8 and CD4 can form memory cells.
The presence of high titers pathogen-specific IgM without detectable IgG most likely means that ________.
The animal was infected very recently.
ELISA is performed to determine what?
- Serum antibody levels to a particular pathogen.
- Particular antigen on a pathogen.
Which statement about germinal center responses is correct:
a) are the most effective means of inducing B cell responses to carbohydrates and lipids.
b) require follicular DC to travel into the B cell follicle to present antigens to B cells.
c) Result in the development of short-lived plasma cells that are localizing to the medullary cords of lymph nodes and the red pulp of the spleen.
d) Initiate after T-B interaction, require CD4 T cells, B cells and follicular DC.
a) GC response to increase affinity of Ig.
b) This is when B cell was presented with antigens.
c) Plasma cells migrate to bone marrow.
d) Require T cell and B cell to bind to activate B cell, then FDC comes in to present antigen to Ig of B cells to see if Ig can have high affinity to bind that antigen.
Immunization leads to the deposition of antigen into the skin. What cells are facilitating antigen transport to the draining LN?
Internalization by DC, which migrate to T cell zone of draining LN.
(B cell needs T cells to be activated or B cells have to bind to polyvalent antigen without DC).
Link recognition is where
a) B and T cells both recognize exactly the same epitope
b) B and T cells recognize the epitopes from the same antigen.
c) B cells are presenting antigen to a CD4+ T cell in a SLO.
Both b and c.
They have to recognize each other via the epitopes (not necessary the exact epitope) and B cell present the antigen to T cell.
Activation of naive T cells in a normal host to produce an effective response requires what?
3 signals:
- peptide:MHC complex
- Co-stimulation molecule
- Cytokines
In the germinal centers,
a) B cells can develop high-specificity antibody in the absence of T cells.
b) Somatic hypermutation produces BCR with higher and lower affinity for the epitope.
c) Somatic hypermutation produces BCR with only higher affinity for the epitope.
B. Somatic hypermutation produces BCR with BOTH higher and lower affinity for the epitope. They do that in the presence of B cells, CD4 T helper, and FDC.
During T cell activation “signal 3” (cytokines produced by DC)
a) induce T cell proliferation
b) Directs T cell polarization
c) is not important for inducing T cell responses that are maximally protective.
d) All are correct.
b.
