T Cell Effector Function

Question 1

What are the 4 possible effector T cell types?

Answer 1

Th1 - activates macrophages

Th2 - B cell isotype switching

Th17 - Promote inflammation by neutrophils

Treg - Inhibit T cell functions

Question 2

What are the effector functions of T Helper cells?

Answer 2

Activate CTL and macrophages

Help in antibody production

Help maintain inflammation

Help get rid of parasites

Question 3

What are the effector functions of cytolytic T lymphocytes?

Answer 3

Kill cells harboring intracellular pathogens

Distinguish uninfected from infected cells

Secrete cytokines

Kill tumor cells

Question 4

What is the difference between activation of naive T cells and effector T cells?

Answer 4

Activation requires costimulation with CD80/86

Effector function only requires MHC/TCR binding

Question 5

How do CTL cause cell death?

Answer 5

CTL induced apoptosis

Question 6

What proteins are contained within the CTL graunules?

Answer 6

Perforin - form pores

Granzymes - serine proteases

Granulysin - induce apoptosis

Question 7

How are T cells inactivated?

Answer 7

As pathogen is cleared, T cells begin to express CTLA4 which binds with high affinity to CD80/86 (B7) on APC

This inhibits T cell activation

Question 8

What cells can inhibit a T cell response?

Answer 8

Suppressor T cells (Tregs) - secrete IL-10 and TGFB

Myeloid Derived Suppressor Cells - arginase production and TGFB

Question 9

What are memory T cells?

Answer 9

Generated at the end of the adaptive response, at the point where the pathogen is cleared

Question 10

What are the functions of IL-2 and IL-7/15?

Answer 10

IL-2: Proliferation of T cells following antigen exposure

IL-7/15: survival of T cells following activation

Question 11

What are the three types of memory T cells?

Answer 11

Central - remain in lymphoid tissue (lymphoid and spleen)

Effector - Migrate to tissue, circulate

Resident - don’t recirculate like the other two, remain at the site of exposure

Question 12

How are macrophages activated?

Answer 12

Interaction between class II proteins on the macrophage and TCR of helper T cells (Th1 effector cells)

Question 13

What changes do activated macrophages undergo?

Answer 13

Increase expression of CD40 and TNF receptors

Secrete increased amounts of TNFa (autocrine stimulation)

Autocrine stimulus synergizes with IFN-y

Question 14

What do macrophages do to increase their antimicrobial activity after activation?

Answer 14

Increased NO production

Increased superoxide production

Increased B7 expression

Increased MHC II expression

Question 15

How do B cells produce antibodies?

Answer 15

BCR binds antigen and the complex is internalized

Following cytokine release, a modified form of the BCR is transcribe and translated and secreted

Question 16

What division of immunity is generation of antibodies considered?

Answer 16

Humoral immunity, a part of the adaptive response

Question 17

What part of immunity do antibodies provide their function in?

Answer 17

The innate immune response

Question 18

Can the antibody response improve?

Answer 18

Yes, affinity maturation occurs along with isotype switching

Question 19

What is the T-independent antibody response?

Answer 19

Does not require interaction with a T cell or an APC

B1 cells bind pathogen and gets turned on directly

Usually IgM against bacteria, function in innate responses

Question 20

What is T-dependent antibody response?

Answer 20

Must interact with Tfh that has been activated by a DC

B2 cells

Majority of antibody

Question 21

What are the differences in antibodies produced from the T-independent and T-dependent response?

Answer 21

T-independent: IgM, natural antibodies that function early in innate immunity

T-dependent: IgM, IgG, IgA, IgE, each have a specific structure and function