Introduction To Immunology

Question 1

First examples of immunity

Answer 1

Edward Jenner generating immunity to smallpox with cowpox without inducing disease

Question 2

Innate immune response

Answer 2

First line of defense
Fast but nonspecific
Includes natural barriers that can be mechanical, chemical, microbiological
Uses PRR to recognize PAMPs on threats

Question 3

Innate immune cells

Answer 3

Macrophage receptors recognize the cell surface carbohydrates of bacterial cells but not human cells.
Natural killer cell receptors recognize changes at the surface of human cells that are caused by viral infection

Question 4

Macrophage receptors

Answer 4

Question 5

Adaptive immune response

Answer 5

Uses B and T lymphocytes
Slow to respond but more powerful than innate immune response ~5-6 days or more.
Uses randomly generated antigen receptors
Humoral and cell mediated responses
Can secrete factors that act systematically and locally
Has memory
Clonal selection

Question 6

Immune cell origination

Answer 6

All immune cells and blood cells are derived from hematopoietic stem cells
Hsc can differentiate into many types of blood cells during hematopoiesis

Question 7

Steps of hematopoiesis

Answer 7

Occurs in bone marrow in adult vertebrates.
Two main types of progenitor cells
Common myeloid progenitor
Common lymphoid progenitor

Question 8

Cells from common myeloid progenitors

Answer 8

Megakaryocytes-form platelets, largest and rarest cell in bone marrow.
Erythrocyte- red blood cells, anuclear
Granulocytes- neutrophils, basophils/mast, eosinophils
Monocytes- differentiates into macrophages and dendritic cells

Question 9

Neutrophils

Answer 9

cause direct harm to pathogens, multi-lobed nucleus, short lifespan of 6hrs. Stored in bone marrow, phagocytoses and shoots granules and nets

Question 10

Basophils and mast cells

Answer 10

Cause inflammation
Basophils produce and release heparin and histamine
Mast cells are similar mostly involved in allergic reactions. Can reside in many organs.

Question 11

Eosinophils

Answer 11

Have antiviral and anti parasite activity

Question 12

Monocytes

Answer 12

Weakly phagocytic, secrete chemokines and cytokines. Main function is to differentiate into macrophages and dendritic cells
3 main subtypes
Classical
Non-classical
Intermediate

Question 13

Macrophages

Answer 13

Similar to neutrophils, great at phagocytosis
Have extended pseudopodia to capture bacteria or antigens. Then broken down in phagolyosomes
Can be inflammatory or anti-inflammatory

Question 14

Dendritic cells

Answer 14

Monocytes can differentiate into the dendritic cell
Highly specialized antigen capturing cells have pseudopodia to sense and detect threats
Immature until they encounter antigen
Most efficient type of cell called the antigen presenting cell or APC

Question 15

Antigen presenting cells

Answer 15

Monocytes, macrophages, and dendritic cells
3 main functions
Internalize pathogens present peptides on their membrane surfaces via MHCs
Secrete cytokines and chemokines
Upregulate costimulatory molecules for optimal activation of helper T cells

Question 16

Main cell types from common lymphoid progenitors

Answer 16

T-cells, B-cells and natural killer cells

Question 17

T-cells

Answer 17

Generally helper and cytotoxic can be further differentiated

Question 18

B- cells

Answer 18

Main function is to secrete antibodies
Can function as APCs
Can differentiate into terminal effector plasma cells

Question 19

Primary immune organs

Answer 19

Sites where hematopoiesis occurs and or cells are developed
Bone marrow is primary organ
Thymus creates thymocytes or T cells-develop in bone marrow first then travel to thymus

Question 20

Thymus zones and pathway of T-cells

Answer 20

Made up of two zones
Medulla and cortex
Immature pre-T cells enter the thymus at the cortico-medullary junction and migrate to the sub-capsular cortex
As they move down the cortex they encounter specialized epithelial cells and apcs and undergo selection
After selection they leave the thymus and enter periphery
Mature but naive

Question 21

Secondary lymphoid organs

Answer 21

Places where cells encounter antigens
Become activated
Undergo clonal expansion
Differentiate into effector cells
Connected via blood and lymphatic system

Question 22

Flow of lymphocytes in lymphatic system

Answer 22

Naive lymphocytes arrive at lymph nodes in arterial blood
Mature dendritic cells activate naive T cells in lymphoid organs

Question 23

Lymph node areas

Answer 23

Cortex is outermost layer contains lymphocytes-mostly B-cells, macrophages, and follicular dendritic cells
Within cortex is specialized B cell zones called follicles- B cells navigate and mature
Paracortex- beneath the cortex populated by T-cells and APCs
Medulla- innermost layer lymphocytes exit through efferent lymphatic vessels

Question 24

Spleen zones

Answer 24

Red pulp: populated by red blood cells, macrophages, lymphocytes
Marginal zone: populated by specialized dendritic cells, macrophages and B-cells found in between red and white pulps. First line of defense against blood borne pathogens.
White pulp has two different zones follicles and periarteriolar lymphoid sheath(PALs)
Follicles are the home for B-cells
PALs house T-cells

Question 25

Alternative immune organs

Answer 25

Gut associated lymphoid tissue (GALT)-tonsils, adenoids, appendix, Peyer’s patches Mucosal associated lymphoid tissues (MALT) Bronchus associated lymphoid tissue (BALT) Nasal associated lymphoid tissue (NALT) Skin associated lymphoid tissue (SALT)

Question 26

Tertiary lymphoid tissue

Answer 26

An active area of infection or immune activity Can be an aggregation of lymphoid or immune cells that develop microstructures to allow coordinated attack Often found in sites of chronic infection.