Cells and Organs of Immune System

Question 1

Pathogens (entry, cell types infected, replication, tissues infected)

Answer 1

entry: skin=malaria

gut=salmonella

cells infected:epithelia-chlamydia

immune cells-HIV

where pathogens replicate:intracellular-viruses

extracellular-parasites

tissues infected:brain-toxoplasma

blood/heart-filarial nematode/heartworm

lungs-flu

Question 2

Migration of dendritic cells to lymph nodes

Answer 2

dendritic cells are activated when they recognize certain characteristic features of microbes

once activated, dendritic cells migrate to lymphoid tissue to initiate lymphocyte (adaptive immune) response

free antigen delivered to lymphoid organs through lymphatic system

Question 3

Activation of lymphocytes

Answer 3

B and T lymphocytes circulate thru lymphoid organs

Free antigen can activate antigen specific B cells

Activated dendritic cells activate T cells (clonal selection)

Activated lymphocytes divide and expand

Question 4

B lymphocyte effector functions

Answer 4

Acitvated B cells produce antibodies. they circulate, bind to microbial antigens and have antimicrobial effects

neutralization, opsonization, complement activation

Question 5

T lymphocyte effector functions

Answer 5

Cytotoxic T cells: migrate back to site of infection and kill microbe infected cells

Helper T Cells: major source of cytokines

• stay in lymphoid and help B cells differentiate into antibody producing cells

or

• migrate to the site of infection and help activate macrophages to be come more effective phagocytes

Question 6

Macrophages

Answer 6

Express pattern recognition receptors that recognize pathogens

Specific pathogenic stimuli can lead to differential response by macrophage

Major function:ingest and kill microbes

After activation–> secrete cytokines that include specific responses to clear specific pathogens

Induce repair of wounded tissue

Question 7

Monocytes

Answer 7

Bean or U shaped nucleus with abundant cytoplasm

2-8% of circulating WBC’s

Become macrophages in tissues

Differentiate into activated macrophages

Question 8

Neutrophils

Answer 8

Functions: phagocytosis, bacterial killing

Filled with granules that have microcidal properties

Immediate responders to inflamed tissues

Question 9

Eosinophils

Answer 9

Remove foreign material bound to antibody

Bilobed nucleus

Question 10

Mast cells

Answer 10

Granules contain histamine and other cytokines that can anti helminth or allergic responses

IgE crosslinking induces mast cell degranulation

mostly in tissues

Question 11

Basophils

Answer 11

Release histamine

May be involved in T cell response

Bilobed nucleus

Question 12

Blood cell counts

Answer 12

Inflammatory mediators

WBCs always circulating in blood cells

massively expand when sick

can go into tissues

Question 13

Lymphocytes

Answer 13

Spherical nuclei

B cells=25-30% of circulating lymphocytes AR=Ig, immunoglobulin or antibody

T cells=65-75% of circulating lymphocytes, AR=T cell receptor

NK cells innate but look like lymphocytes

Question 14

Pathogen clearance

Answer 14

Uses different responses to clear

Antibody is a circulating molecule

Question 15

Hematopoesis

Answer 15

Process of developing immune subtypes

Immune cells come from hematopeitic stem cell

Question 16

Thymus

Answer 16

T-cell origin

bilobed structure in anterior thoracic cavity

Cortex-maturation of thymocytes and development of tolerance

Mature T cells migrate into medulla, enter circulation, seed secondary lymphoid organs

Question 17

The lymphatic system

Answer 17

Lymph is plasma filtrate present in interstitium of tissues throughout body

Lymph nodes are small, nodular structures that drain lymph from skin, mucosal surfaces, and internal organs through LN’s ultimately returning lymphs back to circulation

Antigens carried to LN’s via lymph

Question 18

Lymph nodes

Answer 18

site of adaptive immune activations

affarent lymphatics carry lymph to LN’s, efferent carry lymph away from LN to the next LN in the chain

Lymph is delivered from thoracic duct to the blood via the anterior vena cava

Question 19

B cells and T cell segregation

Answer 19

B cell follicals have stromal cells that produce chemokines that attract immune cells CXCL13(t cells dont have this)high endothelial venules

T cells have CCR7 which binds to CCL19 CCL21

Each go to signal

Question 20

Spleen

Answer 20

ULQ of abdomen, filters blood

Clear RBC’s

Have white pulp- B and T cells

Pals-major site of immune response to blood borne antigens

Question 21

Cutaneous and Mucosal Immune Systems

Answer 21

In continuous contact with external environment

High level exposure to pathogenic and non pathogenic foreign antigens

Regional immune response can happen at MALT,BALT,GALT

Question 22

Integrins

Answer 22

If lacking, will have leukocyte adhesion deficiency (immunodeficient)

Therapeutics against integrins approved for use in autoimmune disorders (MS, Chrons)