Brand notes

Dear everyone,
Do look at the review article associated with this one. It helps. Also, my hands are starting to hurt more, so my notes will be getting a little more terse, if that is possible. And if the professor hands out complete works in class, I won't be typing anything in excess. That's why Nelson's lectures are not posted. Here are my notes on Brand:

Regulation and control of Immune Function: Tolerance
He works with regulatory Tcells.
Big questions on slide 2.
3: checkpoints are there to minimize generation of self –reactive lymphocytes. A few escape.
4: layers of self-tolerance
peripheral anergy- cells get weak signal without costimulus.
clonal exhaustion- signalled for death in secondary lymphoid tissue- similar to selection process, but later
cytokine deviation- instead of becoming a TH1, Th0 directed to become a more suppressive TH2.
we will focus on regulatory cells.
8: induced tolerance- we use processes that take place naturally to our advantage
intravenous tolerance or mucosal.
induced RA-adjuvant and collagen produces a model of arthritis in mouse. feed soluble collagen, or give IV before injecting the collagen+adjuvant- no disease.
12: specific mechanisms in gut help us tolerate food proteins. Lack of costimulation, cells, etc.
14: It is a normal process for self-reactive lymphocytes to make it to periphery. If regulatory T cells are deleted from normal blood, and you move the blood into an athymic system, get autoimmunity.
CD4CD25 double + cells keep autoimmunity in check.
15: + selection for Treg is higher affinity than T effector cells. State of heightened activation CD25 is elevated early in periphery on them (normally in proliferating cells). regulatory T cells suppress effector T cells. Problems when these do not work are listed on the slide. Some tumors may be allowed by too much regulation.
16: Remove thymus around day 3, systemic autoimmunity ensues. If give adult spleen cells- no disease because of regulatory T cells.18: How to identify
Naive animal- double positive is Tregulatory. In vitro- CD25 goes up in other T cells, too.
19: Fox p3 is a nuclear transcription factor. It is in the nucleus, so not good for functional studies.Can’t fish out Tregs very easily using foxp3, because you have to fix and permeabilize the cell. IS specific to Tregs.
Problem: no unique cell surface molecule to discriminate. We trade purity of preparation for getting most of them or vice versa.
22: Mutating foxp3 results in lethal autoimmune problems
25: Tnfrs18 encodes GITR. (glucocorticoid induced TNF-receptor family-related gene/protein), which is a potential marker for Tregs, though not exclusive.
CTLA-4 is uniformly upregulated on Treg cells- negative regulator.
Flow cytometer distinguishes cells based on size and granularity. With antibodies, can look at specific proteins on surface.
34: Tube of cells placed on cytometer. Data is collected on relative fluorescnece while cells go through.
Cells have been fixed and permeabilized so that antibodies can get in.
37: CD25 is found in a spectrum in T cells in the spleen
Lymph node- most regulatory Ts express higher CD25.
39: Transgenic mouse with TcR specific for collagen. Administer collagen- Tregs become 42% of peripheral T cells in blood!
40: AIR gene- autoimmune regulator gene in thymus- produces 2-3,000 peripheral proteins in thymus for negative selection of high-affinity cells.
43: In synovial fluid in autoimmunity, lots of antiself T cells are there- and lots of regulatory Ts. Looks like where autoimmunity is happening, the regulatory T cells are there.
46: look at foxp3 vs GITR- good correlation. May be differences between cells with foxp3 that are bright or dark for CD25. Mice given GITR low cells died earlier.
Mice with CD25 had a different spectrum of diseases. Take away GITR high- may be taking away more Tregs.
GITR and CTLA-4 are used to delimeate Tregs.
Cannot use a single marker yet. combinations work better, but you miss some cells. These markers are higher on Tregs.
Read the review paper in his file on blackboard.
Tregs depend on IL-2 for survival from effector cells (drives proliferation), but they downreg IL-2 transcription in those cells. without it, get autoimmune disease. High doses IL-2 upregulate CD25 expression.
55: Take home- balance between autoreactive T cells and regulatory T cells. All this is being worked out now.
CTLA-4 delivers a suppressive signal. Anti CTLA4 antibodies increase autoimmune responses. BUT CTLA-4 deficient mice can have Treg-like cells . Exact mechanism of suppression is not worked out.