Term
When are glands of the thymus colonized by hematopeietic stem cells?
When does the thymus begin to produce T cells?
When do T cells begin to leave the thymus? |
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Definition
- 7-8 weeks
- 12-13 weeks
- end of week 13, beginning of 14 |
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Term
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Definition
- large deletion in chromosome 22 which is cuased by an error in recombination
- no thymus present at all = complete T cell deficiency/immunodeficiency |
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Term
FOXN1 gene:
- What chromosome
- What does it encode?
- What does a mutation of this result in?
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Definition
- on chromosome 17
- enodes for a transcription factor that is essential for the functional maturation of theymic epithelial cell progenitors
- Immature epithelial cells fail to recruit hematopoietic stem cells into the organ |
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Term
| What is included in the theymic stroma? |
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Definition
| - predominant theymic epithelial cells and fibroblasts |
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Term
Three types of thymic epithelial cells
What are four of their chief functions? |
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Definition
1) cortical
2) medullary
3) Hassal's
1) secrete growth factors (IL 1, 6, 7, SCF, TSLP) required for growth and differentiation of T cells
2) Express cell surface molecules like delta-like 1,4 for the notch receptor
3) Expression of MHC classes I and II/self antigen complexes controls teh selection of maturing T cells
4) Expression of peripheral tissue antigen: insulin |
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Term
Where are macrophages and dendritic cells most common in the thymus?
What do they participate in? |
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Definition
cortical medullary jucntion
- antigen presentation, deletion of autoreactive T cells and phagocytosis of apototic cells |
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Term
| Four types of cells the thymus is responsible for |
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Definition
- cytotoxic T cells (CD8)
- T helper cells (CD4)
- T regulatory cells
- NK T cells |
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Term
What does the notch receptor signify?
What happens immediately after notch signal? |
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Definition
- commitment to being either a T cell or NKT cell (cell can no longer become a B cell)
- the T cell begins to rearrange gamma, delta and beta genes |
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Term
At what stage can T cells develop into either TCRγδ or TCRαβ?
what else is being expressed then? |
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Definition
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Term
What do immature single positive cells express
what makes up preTCR complex? |
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Definition
ISP: CD1A, CD4, CD3
PreTCR complex: CD3, pre-Talpha, and TCRB |
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Term
What do precursors express before notch signal?
What do they express after notch signal? |
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Definition
before: CD34
after: CD34, CD7 (eventually CD1A) |
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Term
Positive selection
What gets shut off after cells make the cut through positive selection and are chosen to proliferate? |
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Definition
Selection of T cells that recognize antiens presented by MHC molecules
- RAG - recombination activating gene: no more gene rearrangements |
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Term
Negative slection
What does it generate? |
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Definition
Deletion of self reactive T cells (ones that bind too strongly to MHC/antigens
- Central tolerance |
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Term
What follows delta, gamma and beta rearrangement?
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Definition
| - beta seleciton of the ISP |
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Term
When does alpha gene rearrangement take place?
What accompanies this? |
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Definition
- following beta selection
- cell at this point is a double positive and will need to downregulate one of the co receptors (either CD4 or CD8)
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Term
What important gene do thymic epithelial cells express that prevents autoimmune disease?
What does it encode for?
Where are cells that express this generally found? |
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Definition
- Auto Immune Regulator Element
- peripheral tissue antigens
- thymic medullary cells |
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Term
Major difference between TCRγδ and TCRαβ?
Two main types of TCRγδ: |
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Definition
TCRγδ receptors bind antigens directly (no MHC needed!)
Two main types:
1) those that express δ1
2) those that express TCRγ9δ2 (majority) |
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Term
TCRγδ1
Location
Two functions |
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Definition
1) populat epithelia (intestines and skin)
2) recognize stressed cells and lipid antigens presented by CD1B or CD1C |
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Term
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Definition
- transmembrane protein distantly related to MHC, present to TCRγδ1.
CD1B and CD1C associate with B2 microglobin |
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Term
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Definition
- recognzie non-peptide pyrophophomonoester antigens foundo n bacteria and malaria parasite.
- produce interferon-γ |
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Term
At what stage do NKT cells develop from thymocytes?
What do they express?
What are their main markers?
Where do mature NKT cells go? |
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Definition
- at double positive cells when presented by CD1D
- CD4pos or CD4 neg, CD8neg
- NK marker: CD56
- T cell marker: TCRαβ/CD3 comples
- bone marrow, spleen, liver, lymphnodes
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Term
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Definition
1) Production of INFγ for Th1
2) Produce IL-4 and othe Th2 cytokinds |
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Term
function of T reg cells, what process are they involved with?
What do they express? |
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Definition
- supress auto reactive T-cells dominant tolerance
- CD4 and CD25 |
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Term
| What is dominant tolerance vs central tolerance? |
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Definition
dominant tolerance: supression by CD4,CD25 T reg cells of autreactive cells that escape negative selection
Central tolerance: destruction of autoreactive T cells (i.e. those who bind too strong to MHC) during negative selection |
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Term
| Treg can also develop in the periphery, what cytokine is necessary for perhipheral Treg development? |
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Definition
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Term
| What gene is involved with IPEX? What cell type is missing? |
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Definition
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