Autoimmunity 1

Question 1

Are natural killer cells part of the innate or the adaptive immunity?

Answer 1

innate

Question 2

Contrast cell mediated and humoral adaptive immunities.

Answer 2

cell mediated defends against intracellualr microbes (Tcell mediated) while humoral defends against extracellular microbes and toxins (B-cell/antibody mediated)

Question 3

What is the action of the T-cell receptor (generally speaking)

Answer 3

TCR recognizes peptide antigen with MHC on cells (each T cell clone is specfic to certain antigen

Question 4

How can you tell if a group of T-cells is malignant?

Answer 4

if they are all clones, ie. No rearrangement of TCR, the group of cells is malignant

Question 5

What cluster differentiation molcule is used as a T-cell marker?

Answer 5

CD3 is linked with TCR and s specific T-cell marker

Question 6

What are the two subsets of cell types a/B associated with TCR?

Answer 6

CD4 (helper Tcells) and CD8 (cytotoxic T-cells

Question 7

What types of cells to CD4 and CD8 cells bind to?

Answer 7

CD4 bind to class II MHC on APC’s, CD8 bind class I on any cell

Question 8

If a Tcell doesn’t express a/B with its TCR, what other set of proteins does it likely express?

Answer 8

a minority of T cells have gamma/delta TCR and do not require MHC for antigen recognition

Question 9

What CD molecule do both CD4 and CD8 cells express?

Answer 9

CD3, they are both T-cell subtypes

Question 10

What is needed for T-cell activation.

Answer 10

T-cells need two signals for activation both antigen/MHC combination engaging TCR/CD4 or 8 AND CD28 engaging B7 on APC

Question 11

Without second signal, T-cells …

Answer 11

fail to respond, undergo apoptosis or become unreactive (anergic)

Question 12

Once activated T-Cell produce what cytokine?

Answer 12

IL-2 which acts to activate other T-cell and as a self-stimulant, this stimulation causes B cell differentiation into effector and memory cells

Question 13

What molecule is used in clinical cell typing?

Answer 13

MHC molecules

Question 14

MHC class II molecules are present on only what type of cell?

Answer 14

antigen presenting cells, in contrast with MHC class I cells which are present on all nucleated cells

Question 15

Approximately 60% of mature Tcells are CD4+ ____ T-cells tha secrete ____ to help macrophages and B-cells fight infection.

Answer 15

helper T cells; cytokines

Question 16

About 30% of T-cells are CD8+ ____ T-cells that destroy host cells that ______ _____.

Answer 16

cytotoxic T cells; contain pathogen/ present pathogen

Question 17

Contrast the action of CD4+ helper T cells and CD8+ cytotoxic T cells

Answer 17

CD4+ secrete cytokines and act as mast regulators of virtually all immune cells while CD*+ cells kill other cells

Question 18

What are the 3 functionally distinct CD4+ T cell populations?

Answer 18

TH1 cells, TH2 cells and TH17 cells

Question 19

Contrast the secretions of TH 1,2, and 17 cells

Answer 19

TH1 secrete interferon gama , TH4 secrete IL-4 and IL-5 and T17 cells secrete IL-17

Question 20

What is the action of TH1 cells

Answer 20

macrophage activation and stimulation of opsonizing IgG antibody production

Question 21

What is the action of TH2 cells?

Answer 21

stimulate IgE and eosinophil activation

Question 22

What is the action of TH17 cells?

Answer 22

recruit neutrophils-acute inflammation and monocytes

Question 23

B-cells arranged in aggregates are called ____ ____

Answer 23

lymphoid follicles

Question 24

Describe the specific receptors used by B-cells to recognize antigen.

Answer 24

surface antibodies IgM and IgD bind the antigen

Question 25

Once stimulated, B cells become ___ ____ which secrete ____

Answer 25

plasma cells, immunglobulins (antibodies)

Question 26

How are macrophages/monocytes activated?

Answer 26

activated by INF-gamma produced by TH1 CD4+ T cells

Question 27

What MHC class are macrophages? What process increases phagocytosis by macrophages?

Answer 27

APC with Class II MHC, phagocytosis is increased by opsonization of microbes by factors like IgG and C3b

Question 28

Name the two different types of dendritic cells.

Answer 28

interdigitated and follicular dendritic cells (some overlapp)

Question 29

Describe the characteristics of interdigitating dendritic cells.

Answer 29

IDC are the most important APC for primary repsonse, located in the epithelium/interstitium and have numerous fine process which increase SA and MHCII and antigen receptors

Question 30

Describe the characteristics of a follicular dendritic cell.

Answer 30

important APC for ongoing immne response, located in the germinal centers of lymphoid follicles and trap bound antigen with Fc, IgG and C3b receptors and present antigens to B cells for activation

Question 31

What is the action of natural killer cells?

Answer 31

aka large granular lymphocytes, they kill virally infected and tumor cells; but do not require prior sensitization

Question 32

What are the two ways that NK cells recognize and target other cells?

Answer 32

1. antibody dependent cell mediated cytotoxicity (with CD16 as an Fc receptor for IgG) and 2. monitoring of class I MHC molecules

Question 33

Describe the inhibitory signal of NK cells.

Answer 33

if cell presents a self/class MHC complex, this binds the NK inhibitory receptor, viruses inhibit MHC expression, which means inhibitory receptor is not engaged and cell is killed