Cellular Immunity

Question 1

How are antigens taken to lymph node

Answer 1

When there is injury, dendritic cells take up and move to lymph node via lymphatic system

Question 2

Nonbacterial vs bacteria engulfment by macrophage

Answer 2

Bacteria - PRRs stimulated, B7 expression induced, signal 2 delivered, T cells activated

Question 3

3 signals

Answer 3

Activation - this is MHC/TCR interaction with CD4 or CD8

Survival - This is coreceptor B7 interacting with B7

Differentiation - production of cytokines from APC to the T cell

Question 4

Dendritic cell in tissue vs. lymph node

Answer 4

In tissue - highly phagocytic, lower MHC expression, B7 not expressed, Ag presentation low

Question 5

Where do lymph nodes receive lymphocytes?

Answer 5

From bloodstream and affarent lymphtics (coming from other lymph nodes)

Question 6

Those T cells that don’t have correct TCR will

Answer 6

Leave through efferent lymphatic vessel to next lymph node

Question 7

T cells that do have correct TCR

Answer 7

Will stay in lymph node to proliferate

Question 8

How do naive T cells enter secondary lymphoid tissues?

Answer 8

Non-specific cell adhesion molecules

Diapedesis

Question 9

once in the secondary tissues, what do naive T cells do?

Answer 9

Bind to APCs via integrins and Ig superfamily molecules…this allows TCR/MHC interaction

Question 10

What is co-inhibitory mechanism

Answer 10

B7 from APC binds CTLA-4 on the T cell

CTLA-4 binds with higher affinity than CD28

Question 11

pSMAC and cSMAC

Answer 11

pSMAC has adhesion molecules needed to attach T cell to Dendritic

cSMAC has CD markers and TCR

Question 12

TCR signaling leads to which TFs

Answer 12

NFAT, NFkB, and AP-1…leads to IL-2 transcription

Question 13

Cyclosporine A

Answer 13

Block NFAT activation

Question 14

Naive T cell TCR vs. mature

Answer 14

Naive - has gamma and beta subunit but not alpha…binds IL-2 with lower affinity

Question 15

End result of IL-2 binding

Answer 15

Secretion of more IL-2 and porliferation

Question 16

CD4 helper T differentiation

Answer 16

All these from dendritic cells

IL12 - Th1 - Cytotoxic
IL4 - Th2 - humoral
IL23 - Th17 - Inflammation
TGFB - Treg (tones down T cell response)

Question 17

Antigen-specific T cell locations

Answer 17

Exposed and trapped in lymph node for a period of time where they won’t be found in efferent lymph

Question 18

CD8 (CTL) cells

Answer 18

Need CD3, CD8, alpha, beta, and T cell to work

Positive and negative selection in thymus

Clonal proliferation…helped by CD4s that secrete IL-2

Question 19

CTL mediated killing

Answer 19

Rapid 
Cell-cell contact
Apoptosis of target 
Killer T can affect multiple targets 
Bystanders unaffected

Question 20

3 steps to CTL killing

Answer 20

Target cell binding
Programming target for lysis (Ca dependent)
Death

Question 21

Perforin

Answer 21

Aids in delivering contents of granules into the cytoplasm…forms pores allowing passage of granzyme

Question 22

Granzyme

Answer 22

Serine proteases that activate apoptosis in the cytoplasm of target cell