Innate Immunity

Question 1

Where are mature T cells found?

Answer 1

In bone marrow, lymph nodes, and spleen, after maturing in the thymus.

Question 2

What are pluripotent HSCs?

Answer 2

Rare, making up 0.05% of bone marrow cells.

Question 3

How can HSCs be mobilized?

Answer 3

From bone marrow to blood for stem cell transplants.

Question 4

What happens to macrophages after activation?

Answer 4

They increase MHC class I & II expression.

Question 5

Where do T cells and B cells develop?

Answer 5

T cells in thymus, B cells in bone marrow and spleen.

Question 6

Where are lymphoid follicles found?

Answer 6

In secondary lymphoid tissues, including MALT.

Question 7

What stimulates infection and inflammation?

Answer 7

Cytokine and chemokine release to boost myeloid lineage development.

Question 8

What do FDCs present to B cells?

Answer 8

Soluble antigen.

Question 9

From which precursors can dendritic cells arise?

Answer 9

Both myeloid and lymphoid precursors.

Question 10

What do B and T lymphocytes have?

Answer 10

Antigen-specific receptors, unlike NK cells.

Question 11

Where are B cells generated in birds and ruminants?

Answer 11

Outside bone marrow.

Question 12

What do myeloid cells include?

Answer 12

Dendritic cells, neutrophils, basophils, and macrophages.

Question 13

What do lymphoid cells include?

Answer 13

NK cells, T cells, B cells, and ILCs.

Question 14

What are secondary lymphoid organs?

Answer 14

Lymph nodes, spleen, and MALT.

Question 15

What are primary lymphoid organs?

Answer 15

Bone marrow and thymus.

Question 16

How do HSCs differ from mature blood cells?

Answer 16

HSCs are multipotent and capable of self-renewal.

Question 17

How does the thymus avoid autoimmune responses?

Answer 17

Negative selection of thymocytes that bind self-antigens with high affinity.

Question 18

When is the thymus at its maximal size?

Answer 18

During puberty, then gradually atrophies.

Question 19

What happens to immunodeficient mice in HSC enrichment?

Answer 19

Stem cells restore immune cells, showing successful enrichment.

Question 20

What are monocytes?

Answer 20

Blood precursors of macrophages with limited phagocytic capacity.

Question 21

How do macrophages compare to monocytes?

Answer 21

Larger than monocytes, with enhanced phagocytosis and cytokine secretion.

Question 22

What happens after bursectomy in chickens?

Answer 22

Leads to lack of B cells and humoral immunity.

Question 23

What is the major antigen-presenting cell for naïve T cells?

Answer 23

Dendritic cells.

Question 24

What is the phagocytic cell in the CNS?

Answer 24

Microglial cells.

Question 25

Which granulocytes act against parasites?

Answer 25

Eosinophils.

Question 26

What gives rise to red blood cells?

Answer 26

Myeloid dendritic cells and HSCs.

Question 27

What are the first cells to arrive at an inflammation site?

Answer 27

Neutrophils.

Question 28

What maintains HSCs?

Answer 28

Osteoblasts.

Question 29

What gives rise to thymocytes?

Answer 29

Hematopoietic stem cells (HSCs).

Question 30

What do monocytes differentiate into?

Answer 30

Macrophages in tissues.

Question 31

What is the antigen-presenting cell from the same precursor as T cells?

Answer 31

Lymphoid dendritic cells.

Question 32

What samples antigen in the intestinal lumen?

Answer 32

M cells.

Question 33

Which granulocytic cells release pharmacologically active substances?

Answer 33

Eosinophils, mast cells, neutrophils.

Question 34

Which cells are involved in allergies?

Answer 34

Eosinophils and mast cells.

Question 35

Which cells express antigen-specific receptors?

Answer 35

Lymphocytes and NKT cells.

Question 36

What are cells with a common progenitor to T and B cells but no antigen receptors?

Answer 36

Innate lymphoid cells.

Question 37

Where is NFAT located under resting conditions?

Answer 37

In the cytoplasm.

Question 38

Where is NFAT located under activated conditions?

Answer 38

In the nucleus.

Question 39

What causes NFAT relocalization?

Answer 39

Dephosphorylation by calcineurin, activated by calcium-calmodulin.

Question 40

What is the effect of cyclosporin on NFAT?

Answer 40

Inhibits calcineurin in T cells, preventing NFAT activation.

Question 41

What do immunoglobulin and TCR binding antibodies share?

Answer 41

Both share the immunoglobulin fold, allowing cross-reactivity.

Question 42

What happens during receptor-ligand binding?

Answer 42

Activates the receptor, causing phosphorylation and receptor cross-linking.

Question 43

What does reduction and alkylation of antibody do?

Answer 43

Breaks disulfide bonds and prevents reformation, allowing study of chains.

Question 44

What does papain digestion of antibody produce?

Answer 44

Produces two Fab fragments and one Fc fragment, revealing antigen-binding sites.

Question 45

How are immunoglobulin fragments detected?

Answer 45

Antibodies against Fab and Fc show contributions of heavy and light chains.

Question 46

What is ITAM?

Answer 46

Immunoreceptor tyrosine-based activation motif, phosphorylated during receptor activation.

Question 47

How are ITAMs in Igα and Igβ modified?

Answer 47

Phosphorylated by Lyn, a Src-family kinase, upon BCR activation.

Question 48

What is an adapter protein?

Answer 48

Brings other proteins together without enzymatic activity.

Question 49

What do SH2 proteins do in TCR signaling?

Answer 49

SH2 domains of ZAP-70 bind phosphorylated ITAMs to activate signaling pathways.

Question 50

How do IgM and IgG compare in antigen-binding?

Answer 50

IgM binds more antigenic sites but not necessarily five times more due to steric hindrance.

Question 51

What happens during cytokine receptor binding at low concentrations?

Answer 51

Activation may increase receptor affinity, such as with IL-2R.

Question 52

How is Src-family kinase activity regulated?

Answer 52

Phosphorylation on inhibitory or activating sites regulates kinase activity.

Question 53

What happens if Lck is inactive in a T-cell clone?

Answer 53

T-cell activation will not occur, preventing IL-2 secretion.

Question 54

What is the protein defective in X-linked agammaglobulinemia?

Answer 54

Btk defects impair B-cell signaling and differentiation.

Question 55

What do short BCR and TCR cytoplasmic regions do?

Answer 55

Signal transduction complexes (Igα/Igβ or CD3) transduce signals despite short regions.

Question 56

What is the first adaptation of antibody structure?

Answer 56

Y-shape with flexible hinge for binding to multivalent antigens.

Question 57

What is the second adaptation of antibody structure?

Answer 57

Variable regions with hypervariable loops to form diverse binding sites.

Question 58

What is the third adaptation of antibody structure?

Answer 58

Constant regions enable interaction with phagocytes and complement proteins.

Question 59

What happens in a constitutively active T-cell clone with Lck mutation?

Answer 59

Lck mutations lead to continuous activation and IL-2 secretion.

Question 60

What is pleiotropy?

Answer 60

One molecule causing multiple effects in different cells.

Question 61

What is synergy in cytokine signaling?

Answer 61

Two or more cytokines producing a response greater than the sum of their individual effects.

Question 62

What is redundancy in cytokine signaling?

Answer 62

Multiple cytokines can produce the same effect.

Question 63

What is antagonism in cytokine signaling?

Answer 63

Two cytokines causing opposite effects or inhibiting each other’s activity.

Question 64

What is cascade induction?

Answer 64

Cytokine triggers other cytokine secretion, amplifying the immune response.

Question 65

How does cytokine signaling affect lymphocyte location?

Answer 65

Induces expression of receptors to alter migration and retention.

Question 66

What do type I interferons do?

Answer 66

Activate ribonucleases to degrade viral RNA, inhibiting replication.

Question 67

What is the effect of defective common γ chain in immunodeficiency?

Answer 67

Prevents binding of multiple cytokines, impairing signaling.