T cells and MHC in Adaptive Immunity

Question 1

Antibodies produced by B cells play a critical role in neutralizing antigens ____ cells, such as free virions or bacteria encountered in the blood or mucosal surfaces ____ pathogens are susceptible to killing by T cells an their products

Answer 1

outside; intracellular

Question 2

T cells interact with foreign antigens that have been processed and then presented on the surface of the host cells in conjunction with molecules encoded by what?

Answer 2

the MHC

Question 3

the alpha beta TCR is on ___% of all T cells and responds to what?

Answer 3

95; responds only to protein antigens

Question 4

the gamma delta TCR is on ___% of all T cells and is found where?

Answer 4

5; mucosal epithelial sites such as the skin, gut, and lung

Question 5

the gamma delta TCR is used as defense against ____, and most are ___ cells

Answer 5

bacteria; cytotoxic

Question 6

the gamma delta TCR recognizes lipid, phospholipid, and glycolipid antigens presented by the ___ molecule

Answer 6

CD1

Question 7

True or false? both types of TCRs have variable and constant regions just like antibody molecules and TCR genes contain multiple exons and rearrange just like antibody genes -> require Rag-1 and Rag-2

Answer 7

true

Question 8

Which molecule is always associated with the TCR and transmits signal to T cell nucleus when TCR binds to antigen

Answer 8

CD3

Question 9

The MHC determines whether a graft will be accepted or rejected and functions in antigen presentation to T cells. True or false?

Answer 9

true

Question 10

The MHC is called the ___ in humans and is encoded on chromosome ___

Answer 10

HLA; 6

Question 11

The following describes what class of HLA molecule?:
composed of alpha chain and beta2-microglobulin; found on all nucleated cells and platelets; present antigen to CD8+ Tc cells; encoded by the HLA-A, HLA-B, and HLA-C genes

Answer 11

Class I HLA

Question 12

The following describes what class of HLA molecule?:
composed of an alpha chain and a beta chain; constitutively expressed on professional APCs; present antigen to CD4+ Thelper cells and Treg cells; encoded by HLA-DP, HLA-DQ, and HLA-DR genes

Answer 12

Class II HLA

Question 13

Class II HLA molecule expression can be induced on other cell types by ____

Answer 13

IFN gamma

Question 14

This is a group of genes that is inherited together as a unit from a single parent

Answer 14

haplotype

Question 15

Humans have two HLA gene haplotypes: one from mom, one from dad. What is the likelihoood that a child will be a perfect HLA match to one of his/her siblings

Answer 15

25%

Question 16

Which HLA molecule would deal with a virus that replicates inside the host cell cytoplasm

Answer 16

Class I HLA

Question 17

In regards to antigen processing for Class I HLA molecules, viral antigens are processed by _____ and then transported by ___ molecules to the ER.

Answer 17

proteasomes; TAP

Question 18

In regards to antigen processing for Class I HLA molecules, peptide fragments leave the ER after being loaded into the Class I molecule and then transported within a ___ body to the ___ of the host cell where Tc cells with ___ specific for the viral peptides are induced to kill the host cell

Answer 18

golgi; surface; TCRs

Question 19

In regards to antigen processing for class II HLA molecules, exogenous antigens are phagocytosed. The phagosome fuses with an ___ ____ which degrades the engulfed microbe into fragments. Meanwhile, class II molecules are being synthesized in the ER of the phagocytic cell, along with an ___ chain

Answer 19

acidic vesicle; invariant

Question 20

In regards to antigen processing for class II HLA molecules,the invariant chain blocks the class II peptide binding groove from what?

Answer 20

becoming loaded with endogenous peptides

Question 21

In regards to antigen processing for class II HLA molecules, when a golgi body containing the class II molecule fuses to the vesicle containing the engulfed microbe, what happens?

Answer 21

the invariant chain is destroyed and the microbial peptides are loaded into the groove of the class II molecules. The class II/microbial peptide complex is then transported to the surface of the host cell for presentation to Thelper cells with the TCRs specific for the microbial antigens

Question 22

T cells require multiple stimuli to become fully activated and capable of cytokine secretion or cytolytic activity. What are the two signals?

Answer 22

signal 1: interaction between tCR and the MHC on the APC; CD4 or CD8 acts as a co-receptor molecule

signal 2: multiple co-stimulatory interaction between cell surface molecules on the T cell and the APC

Question 23

For each of the following co-stimulatory reactions, give the location (T cell or APC) and the function:
CD28/B7
CD40L/CD40
CTLA-4/B7

Answer 23

CD28 on T cell, B7 on APC; function: induces secretion of IL-2 and the expression of IL-2 receptor which are required for T cell activation and proliferation

CD40L on T cell, CD40 on APC; function: enhances CD28-B7 interaction and causes class-switching in B cells

CTLA-4 on T cell, B7 on APC; function: inactivates the T cell, leading to a waning of the immune response

Question 24

What is the major function of CD4+ T cells

Answer 24

cytokine production

Question 25

TH1 cells promote what type of immunity and secrete what?

Answer 25

cell-mediated; IFN gamma, IL-2, TNF beta

Question 26

TH1 development is promoted by _____ and ____

Answer 26

IL-12; IFN gamma note: IL-12 and IFN gamma induce the transcription factor T bet, which directs TH1 development

Question 27

TH2 cells promote what type of immunity and secrete what?

Answer 27

humoral; IL-4, IL-5, IL-6

Question 28

Il-4 produced by mast cells and mature TH2 cells promotes maturation of developing TH2 cells and prevents maturation of TH1 cells. True or false?

Answer 28

true note: IL-4 induces the transcription factor GATA-3 which directs TH2 development

Question 29

TH17 cells promote immunity to what? what do they secrete?

Answer 29

extracellular bacteria and fungi; IL-17, IL-22

Question 30

TH17 development is regulated by what transcription factor?

Answer 30

RORgammaT

Question 31

Treg cells suppress the differentiation and functions of which cells? What do they secrete?

Answer 31

TH1, TH2, TH17 and macrophages; IL-10, TGF beta

Question 32

Treg cells protect the body from autoimmune reactions. What transcription factor regulates Treg development?

Answer 32

Foxp3

Question 33

Mutations in Foxp3 leads to what?

Answer 33

IPEX which manifests with autoimmune enteropathy, psoriasiform, or eczematous dermatitis, nail dystrophy, autoimmune skin conditions such as alopecia universals and bullous pemphigoid

Question 34

In regards to IPEX, ___ are affected, while ___ are carriers and might suffer mild disease

Answer 34

boys; girls

Question 35

The major functions of CD8+ Tc cells are killing of what? What do they secrete?

Answer 35

infected host cells, tumor cells, and foreign tissue grafts; secrete perforin: punches holes in target cell membrane and granzymes: enter the holes and induce caspase-mediated apoptosis

Question 36

Tc cells express the surface protein ___ , which binds to the "death receptor", ___, on the infected cell and induce apoptosis

Answer 36

FasL; Fas (CD95)

Question 37

Apoptotic cells are rapidly phagocytosed, preventing spread of ___ without ____

Answer 37

virions; inflammation

Question 38

____ are microbial toxins that stimulate as many as 1 in 5 T cells. They do not need to be processed by an APC in order to stimulate T cells.

Answer 38

superantigens

Question 39

Superantigens bind simultaneously to class __ MHC molecules and the ___ chain of the TCR

Answer 39

II; beta

Question 40

Superantigens induce release of all the T cell and macrophage cytokines. The most potent superantigens are?

Answer 40

TSST-1: Toxic shock syndrome toxin 1 made by Staph aureus Enterotoxins from S. aureus that cause food poisoning Pyrogenic toxins produced by Strep pyogenes