Pre Exam # 2 Lecture Flashcards Preview

Medical Immunology Bios 443/843 > Pre Exam # 2 Lecture > Flashcards

Flashcards in Pre Exam # 2 Lecture Deck (35):
1

Q # 2 It was stated that the patient, Robert had a wide range of auto-antibodies against various organ specific antigens as well as the liver and skin. How might a defect in normal T cell development lead to auto-antibody production?

No AIRE means no presentation of peptides by thymic medullary epithelial cells. single positive thymocytes cannot undergo negative selection, escape to the periphery, and are able to react with self peptides.

2

What type of signal induces positive selection?

Weak signal

3

What type of signal induces negative selection?

Strong Signal

4

What type of signal produces Treg?

Intermediate signal, causes up regulation of FoxP3; Treg moves to the periphery and suppresses self reactive T cells.

5

Experiments demonstrating negative selection showed that TCR transgenic mice specific for H-Y antigens were deleted in _________ mice

Male transgenic mice

6

Name the three cell surface proteins expressed at the double positive stage?

CD4, CD8, a,b, CD3, complete TCR.

7

Whats at the double negative stage?

CD44, CD25, Kit, pre TCR (rearranged beta chain, PreTalpha)

8

Chaperone proteins that help stabilize class I in the ER include...

Calnexin, Calreticulin, ERP57, ERAP

9

Tapasin

anchors MHC I w/TAP to each other.

10

Peptide binding clefts in class II molecules differ from those in class I molecules in these 2 important ways

Class II has a larger peptide binding cleft (12-16, but upwards of 30+); Class II has four peptide binding clefts in the center; Class II has alpha and beta chain/ Class I has 8 -10 aa binding cleft, shorter, binds two anchor residues towards outside, made up of alpha and b2m chain.

11

TCR resemble the ________ of antibody molecules

Fab

12

This protein is required at the pre T cell stage to induce signaling

CD3 is the signaling portion

13

Most of the variability found in the TCR is found in this region

in the peptide binding region; CDR3

14

Name the two areas of the thymus that are important for positive and negative selection

positive selection occurs in the cortex; negative selection occurs in the medulla

15

A mechanism by which exogenous proteins can be processed and presented to CD8 T cells is known as

Cross presentation (exception to rule # 1); done by DCs; exception to rule #2 autophagy.

16

This cell type is responsible for positive selection

Thymic cortical epithelial cells.

17

This type is responsible for negative selection

Bone derived DCs and macrophages

18

If AIRE is expressed, this cell type plays a role in negative selection

Thymic medullary epithelial cells

19

CD4 T cells express a surface protein that interacts with and binds to this

MHC II

20

What does CD8 bind to?

MHC I

21

At the pre T cell stage, the pre-TCR signals the cell to block ( 1 of four things pre-TCR does)

further b chain rearrangement; alleic exclusion

22

Pre-TCR also signals to initiate (3 things)

alpha chain rearrangement, induces the expression of CD4/CD8, induces proliferation

23

Class I molecules consists of an alpha chain and a

b2m chain (invariant)

24

HLA-DM functions to help class II anitgen processing by

peptide editing, removing CLIP

25

TCR contacts both the MHC molecule and

peptide

26

Most T cell receptors are comprised of _________ and blank______

alpha and beta proteins/ 5% gamma delta

27

Positive selection occurs at this stage of development and assures that the mature T cells are

cortex at the double positive stage; assures that the mature T cells are MHC restricted

28

What is the process that makes thymocytes T cell tolerant

negative selection

29

Deficiency in this ER residing protein leads to an absence of CD8 T cells

TAP1&2/MHC I deficiency; no CD8 T cells

30

The pre TCR is expressed at this stage

double negative ( DN3-4)

31

Class I molecules accommodate peptides of this length

8-10aa; class II 15-30

32

This transcription factor is important to commit HSCs to the T Cell lineage

Notch-1

33

Multiple alleles at each locus of the gene encoding the HLA in a population as a whole is known as

as polymorphism – for class II, most of the polymorphism occurs in the beta chain

34

Polygenic vs polymorphism

How many different HLA molecules do your cells expressed – three class I and three class II (the polygenic is that there are three different class I and class II molecules)

35

This transcription factor regulates expression of tissue specific antigens for tolerance induction

AIRE

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