Cells, Tissues and Organs of the Immune System

Question 1

What are cytokines?

Answer 1

Soluble mediators of communication that immune cells use to communicate with tissue cells via direct cell contact

Question 2

What are chemokines?

Answer 2

Chemical messengers that draw immune cells to a particular site

Question 3

What three principle proteins are located in plasma?

Answer 3

Albumin

Globulins

Fibrinogen

Question 4

What are leukoc

ytes?

Answer 4

True cells with a nucleus and organelles

Proliferate and responsive to cytokine and chemokine signaling

Question 5

What are granulocytes?

Answer 5

Broad term that includes three cell types: neutrophils, eosinophils, and basophils

Granules contain enzymes and other soluble factors necessary for cell function

Question 6

What are neutrophils?

Answer 6

40-60% of peripheral blood

Function as effectors in the initial response to bacterial infection

Phagocytize bacteria

Question 7

What are eosinophils?

Answer 7

Granules contain major basic protein (MBP)

Parasitic infections, allergies and states of hypersensitivity

Question 8

What are basophils?

Answer 8

Granules help mediate inflammatory response

Contain heparin, serotonin and histamine

Question 9

What are mast cells?

Answer 9

Found in tissues with similar function to basophils

Respong to IgE, which will be specific to a particular allergen

When systematically activated, anaphylaxis can occur

Question 10

What are monocytes (or mononuclear phagocytes)?

Answer 10

Differentiate into either professional phagotcytes or dendritic cells (antigen presenting cells)

Question 11

What are dendritic cells?

Answer 11

Derived from monocytes

Heterogenous population of cells which have immunostimulatory capacity

Presents peptides derived from antigens to T cells

Question 12

What are natural killer cells?

Answer 12

Important in early recognition and destruction of virus infected cells and tumor cells

Allows ADCC function

Question 13

What are B lymphocytes?

Answer 13

Make antibodies to extracellular pathogens (humoral immunite

B cell receptor is an exact copy of secreted antibody

Question 14

What are T lymphocytes?

Answer 14

Helper, cytotoxic and suppressor are responsible for eradicating virus infected cells, tumor cells and cell derived from transplant.

Function against intracellular pathogens

Question 15

What are memory cells?

Answer 15

B cells that have remained after an immune response

Rest of the population dies

Question 16

What are the three types of T cells?

Answer 16

Helper

Cytotoxic

Suppressor

Question 17

What marker is present on all T cells?

Answer 17

CD3+

Question 18

What is the difference between primary and secondary lymphoid organs?

Answer 18

Primary - where immune cells are educated

Secondary - where immune cells perform their effector function

Question 19

What is mucosal-associated lymphoid tissue?

Answer 19

Lymph node-like in subepithelia of all mucosal tissue site

Can be diffuse (intestinal lamina propia) or organized (tonsils, Peyer’s patches, appendix)

Question 20

What is the thymus?

Answer 20

Primary lymphoid organ where precursor T cells undergo differentiation

Involutes with age, so does T cell production

Question 21

What is Central Tolerance Induction?

Answer 21

Process by which lymphocytes that possess reactivity against self are eliminated

Question 22

Describe the bone marrow in the context of the immune system.

Answer 22

Site of B cell development

Site of granulopoiesis

Site of immune reactions, thus considered a secondary and primary lymphoid organ

Question 23

What is the reservoir function of bone marrow?

Answer 23

Bone marrow is an important reservoir for neutrophils

Large number of neutrophils can be mobilized rapidly in response to infections and stress

Question 24

Describe the spleen.

Answer 24

Site of adaptivve immune responses to blood-borne antigens

Red pulp - majority of tissue, rich in macrophages which filter blood of foreign material and aged RBCs

White pulp - multiple immune cell types necessary to initiate adaptive immune response

Question 25

What is the difference between a primary and secondary lymphoid follicle in the spleen?

Answer 25

Primary - naive B cells

Secondary - outer mantle of naive B cells with a germinal center containing activated B cells

Question 26

What are lymph nodes?

Answer 26

Secondary encapsulated lymphoid organs

Occur in chains or groups along lymphatics

Site of adaptive immune response to tissue-borne antigens

Question 27

What are High Endothelial Venules?

Answer 27

Specialized post-capillary venules through which naive lymphocytes enter the lymph node