Lecture 11: Intro to T cells; MHC structure, function and genetics in T cell recognition of antigen

Question 1

Where are T-cells born?

Answer 1

Bone marrow

T-cells originate from hematopoietic stem cells in the bone marrow.

Question 2

Where do T-cell precursors travel to mature?

Answer 2

Thymus

The thymus is critical for the development of T-cells.

Question 3

What are the secondary lymphoid tissues where mature T cells travel?

Answer 3

Lymph nodes, spleen, GALT

Secondary lymphoid tissues are essential for immune response activation.

Question 4

What type of white blood cell are T-cells?

Answer 4

T lymphocytes

T-cells are a crucial component of the adaptive immune system.

Question 5

What are the two main types of mature T-cells?

Answer 5

CD4+ (helper T cells) and CD8+ (cytotoxic T cells)

These T-cells have distinct roles in immune response.

Question 6

What is the primary function of CD4 helper T cells?

Answer 6

Help B cells become plasma cells

CD4 cells assist in B-cell development and antibody production.

Question 7

What do CD8 cytotoxic T cells do?

Answer 7

Directly kill infected or cancerous cells

CD8 T-cells recognize and eliminate cells presenting non-self antigens.

Question 8

True or False: T-cells can develop into multiple types with unique functions.

Answer 8

True

T-cells can differentiate into various subtypes based on signals received.

Question 9

Fill in the blank: T-cells travel via the _______.

Answer 9

Bloodstream

T-cells circulate through the body in the blood to reach lymphoid tissues.

Question 10

What type of immune response do regulatory T cells provide?

Answer 10

Immune inhibition

Regulatory T cells help maintain immune tolerance and prevent overactive responses.

Question 11

What is the role of Th1 cells?

Answer 11

Help macrophages become more phagocytic

Th1 cells enhance the ability of macrophages to engulf pathogens.

Question 12

What is the function of lymph nodes?

Answer 12

Filters for lymph

Lymph nodes trap pathogens and activate T and B cells.

Question 13

What is the function of the spleen?

Answer 13

Filter for blood

The spleen removes old or damaged blood cells and pathogens.

Question 14

What does GALT stand for?

Answer 14

Gut-associated lymphoid tissue

GALT plays a vital role in immune function in the gastrointestinal tract.

Question 15

What are the types of CD4 helper T cells?

Answer 15

Th1, Th2, Th17, Treg, and Tfh

Each subtype has distinct roles in regulating immune responses.

Question 16

What do BCRs recognize?

Answer 16

BCRs recognize any solvable protein.

Question 17

What do TCRs recognize?

Answer 17

TCRs can only recognize peptide portions of antigens presented by MHC.

Question 18

What does MHC stand for?

Answer 18

MHC stands for Major Histocompatibility Complex.

Question 19

What are T-cell receptors (TCRs) made up of?

Answer 19

TCRs are made up of two polypeptide chains that compose one antigen binding region.

Question 20

What percentage of TCRs are composed of alpha and beta chains?

Answer 20

Approximately 95% of TCRs are composed of an alpha and a beta chain.

Question 21

What percentage of TCRs are made up of gamma and delta chains?

Answer 21

The remaining 5% of TCRs are made up of gamma and delta chains.

Question 22

Where are gamma delta cells usually distributed?

Answer 22

cells are usually distributed in peripheral tissue.

Question 23

What is the function gamma delta T cells?

Answer 23

have a similar function to NK cells and play a role in innate immunity.

Question 24

What is sometimes needed for a functional T cell?

Answer 24

Sometimes a CD3 co-molecule is needed to help transduce a signal to activate the T cell.

Question 25

What do T cells secrete?

Answer 25

T cells secrete cytokines and toxic proteins.

Question 26

What is similar to the FAB fragment on antibodies?

Answer 26

The variable region (V) of TCRs is similar to the FAB fragment on antibodies.

Question 27

What is the constant region (C) of TCRs similar to?

Answer 27

The constant region (C) of TCRs is similar to an Ig-like domain.

Question 28

What is the size of the alpha chain of TCRs?

Answer 28

The alpha chain is approximately 40-50 kDa.

Question 29

What is the size of the beta chain of TCRs?

Answer 29

The beta chain is approximately 35-46 kDa.

Question 30

What region of TCRs is exposed for specificity?

Answer 30

TCRs have a CDR exposed region for specificity.

Question 31

What do BCRs recognize?

Answer 31

can recognize antigens via either an energy segment or a 3D structure.

Question 32

How do T-cell receptors (TCRs) recognize proteins?

Answer 32

TCRs do not recognize soluble proteins; they recognize a complex made by peptide and MHC.

Question 33

What is the primary function of the T-cell receptor?

Answer 33

The primary function of the T-cell receptor is to recognize and bind to specific antigens presented by MHC molecules.

Question 34

What is involved in antigen processing?

Answer 34

Antigen processing involves the breakdown of proteins and the presentation of peptides by MHC molecules.

Question 35

What is recognized by the T-cell receptor?

Answer 35

The T-cell receptor recognizes the antigen-MHC complex on the cell surface.

Question 36

What is the ligand for a TCR?

Answer 36

The ligand for a TCR is the combination of peptide and MHC molecule at the cell surface.

Question 37

How is a mature peptide processed to be put in an MHC molecule?

Answer 37

Cut peptides so that multiple inside portions can meet multiple MHCs

Question 38

What do individual TCRs recognize?

Answer 38

Individual TCRs recognize only individual unique MHC-presented peptides.

Question 39

What is T-cell recognition of antigens restricted by?

Answer 39

T-cell recognition of antigens is MHC-restricted.

Question 40

Which T cells can recognize antigens?

Answer 40

Both CD4+ and CD8+ T cells can recognize antigens.

Question 41

When can T cells recognize antigens?

Answer 41

T cells can recognize antigens only when presented in the groove of an MHC molecule.

Question 42

What is MHC restriction?

Answer 42

MHC restriction is the dependence of T-cell receptors on self-MHC.

Question 43

Where does MHC restriction occur?

Answer 43

MHC restriction occurs as T cells are developing in the thymus.

Question 44

What is the survival dependence of T cells in the thymus?

Answer 44

The survival of T cells is dependent on engagement with self-MHC molecules present in the thymus.

Question 45

What happens before T cells mature?

Answer 45

Before T cells mature, a sophisticated screening process occurs.

Question 46

What can T cells weakly bind to during maturation?

Answer 46

Only T cells can weakly bind with their self-MHC and self-peptide.

Question 47

What happens if T cells don't recognize self-peptide-MHC?

Answer 47

If T cells don't recognize self-peptide-MHC, they won't survive or leave the thymus.

Question 48

What do T cells show after leaving the thymus?

Answer 48

After leaving the thymus, T cells show weak binding to self-MHC with foreign peptides.

Question 49

What is a major issue for tissue graft rejection?

Answer 49

Host rejects MHC molecules.

Question 50

What is the MHC gene in mice called?

Answer 50

H2 - a major immune response gene.

Question 51

Who originally identified MHC in mice?

Answer 51

R.A. Gorer and G.D. Snell in the 1930s.

Question 52

What was the basis for defining MHC?

Answer 52

Tissue graft rejection.

Question 53

Who was awarded the Nobel Prize in 1980 for MHC discoveries?

Answer 53

George D. Snell.

Question 54

Who discovered the first compatibility antigen in humans?

Answer 54

Jean Dausset.

Question 55

What did Barui Benacerraf find about immune reactions?

Answer 55

They are controlled by the MHC genes (immune response genes).

Question 56

What did Rolf Zinkernagel and Peter Doherty reveal about T cells?

Answer 56

It is the complex of MHC molecule plus antigen that is recognized by T cells (MHC restriction of T cell responses).

Question 57

Who won the Nobel Prize in Physiology or Medicine in 1996?

Answer 57

Rolf Zinkernagel and Peter Doherty.

Question 58

What was the 1980 Nobel Prize awarded for?

Answer 58

"For their discoveries concerning genetically determined structures on the cell surface that regulate immunological reactions."

Question 59

What are inbred strains of mice?

Answer 59

Genetically identical at all loci

Question 60

What discovery was made from experiments mapping the genetics of transplantation?

Answer 60

The discovery of the MHC

Question 61

What are the genotypes of the parental strains?

Answer 61

b/b and k/k

Question 62

What is the genotype of the F1 progeny?

Answer 62

Heterozygous at all loci (H-2b/k)

Question 63

What is required for skin transplants?

Answer 63

MHC identity

Question 64

What is the recipient type for a skin graft from F1 progeny?

Answer 64

Parental recipient

Question 65

What happens to tissue if MHC identity is not matched?

Answer 65

Tissue will be rejected

Question 66

How many MHCs does each APC have on the surface of the cell?

Answer 66

100,000 MHCs

Question 67

What does MHC stand for?

Answer 67

Major Histocompatibility Complex

Question 68

What is the significance of the experiments mapping the genetics of transplantation?

Answer 68

Led to the discovery of the MHC

Question 69

What are MHC molecules?

Answer 69

MHC molecules are a set of cell surface proteins.

Question 70

What are the two broad kinds of microorganisms that infect human tissues?

Answer 70

1) Extracellular, e.g. bacteria which live and replicate in the space between cells. 2) Intracellular, e.g. virus which live and replicate inside human cells.

Question 71

What is MHC class I associated with?

Answer 71

MHC class I presents endogenous proteins, such as viral or tumor proteins.

Question 72

What is MHC class II associated with?

Answer 72

MHC class II presents exogenous proteins.

Question 73

How do MHC class I and class II differ?

Answer 73

The two types have different pathways for presenting antigens.

Question 74

What forms the peptide binding groove in MHC class I?

Answer 74

MHC class I has a peptide binding groove formed by alpha (α1-3) domains and a beta (β)2-microglobulin domain.

Question 75

What forms the peptide binding groove in MHC class II?

Answer 75

MHC class II has a peptide binding groove formed by two alpha (α) and two beta (β) domains.

Question 76

Which chains in MHC 1 molecule bind to the antigen?

Answer 76

Alpha 1 and 2

Question 77

Which chains in MHC 1 molecule bind to the antigen?

Answer 77

Alpha 1 and 2

Question 78

What part of the MHC 1 complex has a transmembrane domain?

Answer 78

Alpha 3 is the longer peptide that does this

Question 79

What chains on the MHC 2 complex binds to the antigen?

Answer 79

Alpha 1 and Beta 1

Question 80

What chain in the MHC 2 complex is transmembrane?

Answer 80

Alpha 2 and Beta 2 chains

Question 81

What chain in the MHC 2 complex is transmembrane?

Answer 81

Alpha 2 and Beta 2 chains