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Flashcards in formative assesment Deck (15)
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1
Q

what is action of regulatory T cells

A

Regulatory T cells, often described either as CD4+CD25+ or as CD4+Foxp3+ cells play an important role in suppressing immune responses. They can prevent proliferation or cytokine production by other T cell subsets either directly or through their actions on the antigen-presenting cells such as dendritic cells. Regulatory T cells can use different mechanism of suppression including (but not limited to) CTLA4 expression, IL-10 and TGF-1- secretion etc. In some cases the development of these cells is induced by the presence of TGF-1

2
Q

what are dendritic cells

A

Dendritic cells: Professional antigen presenting cells, crucial for bridging innate and adaptive immune response by presenting antigen to naïve T cells. They are often identified by the expression of CD11c. In addition, different dendritic cell populations express additional surface molecules such as Cd11b and CD103. Different transcription factors are known to be associated with particular DC functions (IRF4, Blimp1).

3
Q

what is TGFbeta

A

Transforming growth factor  TGF-β has pleiotropic effects on adaptive immunity, especially in the regulation of effector and regulatory CD4+ T cell responses. Many immune and nonimmune cells can produce TGF-β, but it is always produced as an inactive complex that must be activated to exert functional effects. After it is synthesized, the TGF-β homodimer interact with a Latency Associated Peptide (LAP) forming inactive/ latent TGF complex. The dissociation from LAP is an important to generate active TGF; LAP-TGF can be expressed on the cell surface.

4
Q

what is CpG

A

Synthetic ligand used to stimulate TLR9 (mimic unmethylated CpG sequences in
viral or bacterial DNA)

5
Q

what is cell trace violet

A

a fluorescent reagent/ dye which once inside the cell binds to amine groups in proteins, resulting in long-term dye retention within the cell. Through subsequent cell divisions, daughter cells receive approximately half of the fluorescent label of their parent cells, allowing the analysis of the fluorescence intensities of cells and determination of the number of cell divisions that the cell has been through since the label was applied.

6
Q

what is DTR technology

A

diptheria toxin receptor techonology allows specific cell ablation (the cells which express DTR will be deleted in the presence of diptheria toxin, DT)

it is a useful method for analysing the in vivo function of specific cell populations

7
Q

what is the conditional knockout - CRE/lox system

A

Conditional knockout- CRE/lox system: site-specific recombination system widely used in mice. The enzyme Cre recombinase, originally derived from the P1 bacteriophage, recognizes specific 34 base-pair DNA sequences called lox sites which are added so that they flank a sequence of DNA. This sequence (floxed sequence) can be excised by CRE. Cre recombinase is usually under control of a cell specific promoter allowing for depletion of a particular gene in specific cell type for example Tgfbrfl/flCd11cCRE denotes a mouse where the TGF receptor II gene is flanked by lox sites and CRE is expressed under the control of CD11c promoter (in cells expressing CD11c).

8
Q

how are bone marrow chimeric mice used

A

Bone marrow chimeric mice: Chimeric mice are used to study the contribution of various cell types of hematopoietic or non-hematopoietic origin in the course of an immune response.

recipient mice are subjected to predetermined lethal or sublethal doses of X ray or gamma radiation and then injected with donor bone marrow

9
Q

what are congenic markers

A

congenic is used to refer to the strains which differ genotypically only in one locus of a particular genetic region

for examble in bone marrow transplantation experiments congenic mice with CD45.1 versus CD45.2 (also known as ly5.1 and Ly5.2) alleles are often used

CD45 is common antigen expressed in all leukocytes, 2 different alleles; CD45.1 and CD45.2 are functionally identical an can easily be detected by flow cytometry

10
Q

what are reporter mice

A

for example BlimpGFP : mice GFP tag is inserted into a particular location (in this case Blimp gene) so that expression of GFP is a ‘reporter’ for expression of Blimp.

11
Q

what are OTII transgenic mice

A

transgenic mice express the mouse alpha-chain and
beta-chain T cell receptor (that pairs with the CD4 coreceptor) which is specific for
chicken ovalbumin peptide 323-339; All the CD4 T cells recognise this OVA peptide.

12
Q

how does infection affect risk of pneumonia

A

following severe primary infection the risk of development increases due to acquired immune defects known as sepsis-induced immunosuppression;

leading to the development of DCs and macrophages that are functionally impaired in terms of T cell activation and instead show tolerogenic properties that contribute to immune suppression

risk increases to 30-50% for critically ill patients recovering from first episode of infection

13
Q

what causes tolerogenic differentiation in DCs

A

TGF-beta and Treg cells, these “paralysed” DCs express high amounts of blimp1 and low amounts of IRF4

IRF4 is a transcription factor associated with increased antigen presentation capacity

Blimp1 is a transcription factor associated with tolerogenic functions

14
Q

what is rate of early recurrence of pneumonia in critically ill patients cured from primary pneumonia

A

20%

15
Q

what is used to induce pneumonia in the experiment

A

E.coli bacteria or infleunza A virus (IAV)