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Immunology > T cell Immunity > Flashcards

T cell Immunity Flashcards

Glossary of terms

1
Q

Anergy

A

state of nonresponsiveness to antigen; can’t respond under optimal conditions of stimulation

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2
Q

APC

A

specialized cells that present antigen and display their peptide fragments on the cell surface together with other costimulatory proteins required for activating naive T cells

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3
Q

what are the major APCs that activate naive T cells?

A

dendrites, macrophages, and B cells

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4
Q

B7 molecules

A

major T cell co-stimulatory molecules, B7.1 and B7.2. Closely related and both bind CD28

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5
Q

how many B7 molecules are there? what expresses them?

A

2; APC

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6
Q

What is another name for the B7 molecules?

A

B7.1=CD80, B7.2=CD86

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7
Q

CD28

A

receptor on T cells for the B7 costimulatory molecules

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8
Q

why is Cd28 important?

A

plays a huge role in activation and proliferation of T cells after they first encounter an antigen

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9
Q

Why is CTLA-4 important?

A

high affininity receptor for B7 molecules on T cells; plays a critical role in shutting of the T cell response

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10
Q

Granzymes

A

serine proteases that are involved in inducing apoptosis in the target cells

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11
Q

Homeostatis

A

state of physiological normality; in case of immune system

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12
Q

What does homeostatsis mean in the immune system

A

its state when the person is unaffected (ie numbers of lymphocytes)

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13
Q

IL-2 is

it functions to

A

cytokine produced by activated naive T cells; promote further differentiation and proliferation

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14
Q

why is IL-2 important?

A

key cytokine in development and contraction of the an adaptive immune response

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15
Q

IL-7 is

it functions to:

A

hematopoietic growth factor secreted by stromal cells in the bone marrow and thymus and other cells

promote T cell development, survival, and homeostasis

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16
Q

Perforin

A

protein that can polymerize to form membrane pores that are an important part of the killing mechanism in cell-mediated cytotoxicity

17
Q

Other than stromal cells in the bone marrow and thymus, what other cells secrete IL-7

A

keratinocytes, dendritic cells, hepatocytes, neurons, and epithelial cells

18
Q

what is a naive T cell?

A

Naive T cells have not yet encountered their antigen

19
Q

What are the signals needed to maintain T cell homeostatis?

A

TCR: pMHC interaction

IL-7

20
Q

What are the steps for T cells encountering their antigen?

A
  1. T cells enter a lymph node across a high endothelial venule in the cortex
  2. T cells monitor antigen presented by macrophages and dendritic cells
  3. Cells that do not encounter specific antigen leave by efferent lymph
  4. T cells that encounter their specific antigen proliferate and differentiate into effector cells
21
Q

What are the functions of the accessory molecules?

A

control routes of T migrations, strengthen adhesion with APCs, signal transduction

22
Q

how is control of cell migration routes maintained?

A

selectins, integrins, and chemokine receptors control migration in and out of lymph nodes

control release of effector and memory T cells to site of infection

23
Q

How is the adhesion with APC’s strengthed?

A

integrins;

24
Q

How is affinity of integrins increased?

A

affinity of integrins is increased by cytokines produced during inflammation and Ag recognition

25
Q

What molecules facilitate transduction and how?

A

CD4 and CD8 coreceptors recognize MHC molecules

CD28-CD40L are receptors for costimulators expressed on APCs

26
Q

What is the role of the interaction between ICAM-1 and LFA-1

A

prolongs cell to cell contact between the APC and T cell, as they must be bound for 6-12 hours to activate the naive T cell

27
Q

Describe the process of the T cells and APCs

A

1.T cell binds APC through LFA1:ICAM1, acts as tether
2.subsequent binding of T cell receptor signals LFA1
3. LFA1 undergoes a conformational change that increases the affinity for ICAM1
allows for a stronger interaction between APC and T cell

28
Q

What are the 2 signals required for activating naive T cells?

A

signal 1: antigen recognition

signal 2: microbes or substances released during innate immune response to microbes

29
Q

Why do you need signal 1 (antigen recognition)?

A

ensures that the response is antigen specific

30
Q

Why do you need signal 2? what does it mean?

A

ensures that the immune system is responding to microbes and not to harmless antigenic substances

activated APCs express molecules which in turn bind their respective ligands on T cells to deliver a costimulatory signal.

Immunology (7 decks)

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