Immunology 1

Question 1

Hematopoietic cells

Answer 1

Stem cells that produce;

myeloid stem cells (makes basophils, eosinophils, neutrophils)

and

lymphoid stem cells (mature into T and B cells)

Question 2

Neutrophils (role and characterisitcs)

Answer 2

Innate Immune

Also called polymorphonuclear cells (PMNs) bc their segmented nucleus

Increase in number in response to infection and inflammation (first cells to arrive)

Major line of defense against pus-forming bacteria

Phagocytes - engulf bacteria and produce debris

Granulocytes - have enzymes and proteins that kill invading pathogens or threats

Question 3

Monocytes and MAcrophages

Answer 3

Innate and Adaptive (macro) Immune

long lived cell with bilobed nucleus, originate in bone marrow

In response to infection and inflammation they migrate to the tissue and mature into macrophages

They take over neutrophils and filter the debris they made, kill (phagocytosis) any damaged bacteria or bacteria that was too large for neutrophils

Also eliminate old RBC or dead neutrophils

(They ingest bacteria and use it to express as an antigen on their MHC to signal the T helper cells to respond)

Question 4

Eosinophils

Answer 4

Innate

Involved in allergic responses and parasitic infections

When invading organisms are too large for neutrophils and macrophages to eliminate, eosinophils surround the pathogen and release the contents of their granules to induce membrane damage and death

granule contents:

histamine: vasodilator
heparin: anticoagulant
cytokines: inflammatory reactions

Question 5

Basophils and Mast cells

Answer 5

Innate

Both located close to blood vessels and have similar fxn

Basophils - major role in allergic reactions releases substances from their granules

Mast cells -
- involve in allergic reactions, anaphylaxis, wound healing, and against pathogens
- possess granules containing histamine that dilate blood vessels

Both increase blood supply which recruits more phagocytes to the infected site

Question 6

Erythrocytes and thrombocytes

Answer 6

innate

both responsible for movement and removal of antigens, antibodies and portions of the compliment system

Erythrocytes (RMB) and thrombocytes (platelets)

platelets - hemostasis (stopping bleeding after injury) and thrombosis (blood clots)

Question 7

Lymphocytes (B and T cells)

Answer 7

Adaptive

B lymphocytes - mature in bone marrow, produce antibodies to neutralize pathogens

T lymphocytes - mature in bone marrow and thymus,
- helper t cells
- cytotoxic t cells

Question 8

NK cells

Answer 8

Lymphocytes, Mature cells in the blood and spleen

Kill the cells infected with viruses, other intracellular micro-infected cells and tumor cells

1. localized to infected tissues in response to inflammatory cytokines
2. release cytotoxic granules, create pores in membrane, and activate a programmed death cascade
3. release more cytokines to recruit macrophages and initiate adaptive immunity

Question 9

How are NK cells different that the other lymphocytes (T and B cells)

Answer 9

Unlike T and b cells, NK cells do not express antigen-specific receptors, they express activating and inhibitory receptors on their surfaces that interact with lingads on the target cell

NK cells have special receptors on their surface that help them decide whether to attack a target cell.

After binding, these receptors can either send a “go ahead” signal (activating receptors) or a “stop” signal (inhibitory receptors) based on what they find on the target cell. If a target cell is acting suspiciously (like a virus-infected or cancerous cell), the NK cell will get the “go ahead” signal and attack it.

they use a more general system of activating and inhibitory receptors to determine whether to attack a cell based on its overall condition rather than specific markers. This allows NK cells to quickly respond to a wide range of threats.

Question 10

Phagocytes

Answer 10

Phagocytes readily ingest pathogens and kill them to protect against infection

two principal families of phagocytes
- neutrophils (granulocytes, short lived 2-3 days)
- monocytes (non-granulocytes, months to years)

those undergoing radio or chemo therapy often have decreased amounts of these and re susceptible to infections

Question 11

Antigen Presenting cells

Answer 11

Three major categories: Macrophages, dendritic cells, B cells

They display an antigen to a T cell in order to activate it, which enables the body to see and react to antigens that the body is exposed to

*Display antigens on MHC II
Class I can be recognized by cytotoxic T cells (CD8+)
Class II recognized by helper T cells (CD4+)

Macrophages and dendritic cells display the antigen after phagocytosis while B cells present the antigen through receptor-mediated endocytosis

Question 12

First line of defense

Answer 12

innate immunity

resolve most threats, comprised of early host defense mechanisms

does not remember the interaction with a specific invader, just recognizes repeating patterns of molecular structure that are common to certain classes of pathogens

external and internal defenses

Question 13

external innate defenses

Answer 13

physical, chemical and mechanical barriers that provide protection against invaders

skin, mucus, peristalsis, coughing, sneezing, stomach acid. cerumen, tears, saliva

Question 14

internal innate defenses

Answer 14

1. cellular components (neutrophils, monocytes/macrophages, NK cells)
2. soluble factors (complement system, cytokines, chemokines, acute phase proteins)

chemokines - small cytokines that can chemotactic migration of leukocytes and enhance inflammation

acute phase response - occurs when high levels of proinflammatory cytokines are produced

cytokines - signaling molecules, don’t actually kill pathogens but recruit, organize, signal immune system factors and signal for inflammation

complement system - proteins that kill pathogens or mark them fro destruction, also promote inflammation

Question 15

Secondary line of defense

Answer 15

Inflammatory response

includes the vascular response, the plasma protein system and the complement system

Question 16

Vascular response of the secondary line of defense

Answer 16

vasodilation occurs to increase blood flow and decrease blood velocity

increased permeability allows migration of WBCs across vessel walls (diapedesis)

*cellular debris and fluid eventually drain through the lymphatic system, which helps mature B and T cells of the adaptive immune response

Question 17

Third line of defense

Answer 17

Adaptive (specific) immunity

characterized by specificity and memory

humoral and cell-mediated

Question 18

Humoral immunity

Answer 18

adaptive

involves the production of antibodies by B cells

These antibodies circulate in the blood and lymph, binding to pathogens, marking them for destruction, and neutralizing toxins

Question 19

Cell-mediated immunity

Answer 19

adaptive

involves T cells, another type of white blood cell, which directly attack infected or abnormal cells

When T cells recognize infected cells or cancerous cells through their T cell receptors (TCRs), they can kill these cells directly (cytotoxic T cells) or help activate other immune cells (helper T cells)

Question 20

Active (adaptive) immunity

Answer 20

protection acquired by the introduction of an antigen into the host

can be natural - environmental exposure causes your body to create antibodies

or artificial - vaccine

Question 21

Passive (adaptive) immunity

Answer 21

occurs when immune products such as antibodies or sensitized lymphocytes produced by an immune person are transferred to a nonimmune person

natural - transplacental transfer of antibodies from mother to fetus, mother to infant through breast milk

artificial - admin of immune serum globulin (does not always result in the formation of memory cells)

Question 22

Variable region of antibodies

Answer 22

each antibody made by a B cell has two identical heavy chains and two identical light chains

special bonding forms it into a Y shape

the ends of the Y (where it attaches to the antigen (marker) of a pathogenic cell) are specific to each invader

the ends of the heavy chain and light chain are different from one antibody to the next and are called the variable regions. The V regions contain the HYPERVARIABLE REGIONS or CDRs which play the biggest role in making sure the antibody fits the antigen perfectly

Question 23

*constant regions of an antibody

Answer 23

Heavy chain of antibody (immunoglobin) determines the type of the antibody (IgM, IgG, IgE, IgA or IgD)

Each constant region of the immunoglobin heavy chain is encoded by a gene segment that corresponds to a lowercase Greek letter

Question 24

Major functions of immunoglobins

Answer 24

• directly attack antigens, destroying or neutralizing them through the process of agglutination, toxins, neutralizing antigenic substances and lysing the organism’s cell wall
• activate the complement system
• activate anaphylaxis by releasing histamine
• stimulate antibody-mediated hypersensitivity

Question 25

IgM

Answer 25

u

produced by and expressed on the surface of a B cell

first secreted antibody and is a predominant in a primary or initial immune response

Question 26

IgG

Answer 26

y (gamma)

major antibacterial and antiviral antibody in the blood

synthesized during a secondary immune response (after IgM)

Question 27

IgA

Answer 27

a (alpha)

in serum and secretions (saliva, breast milk, urine, tears, nasal fluids)

defends external body surfaces (mucus membrane)

Question 28

IgE

Answer 28

e (epsilon)

low levels in blood

found bound to high-affinity receptors on mast cells and basophils

fxn during allergic rxns

E for epi pen = allergic

Question 29

IgD

Answer 29

delta

low blood levels

serves as an antigen receptor on mature naive B cells

Question 30

How does the adaptive immune system produce specific responses when there are so many different pathogens that could be present

Answer 30

every characterized antibody molecule has a unique molecular signature in its variable region

B cells - As B cells develop, their DNA goes through permanent changes called gene rearrangement which allows B cells to create millions of different antigen receptors (BCRs) which is how our body can recognize many different invaders. Also, different forms of antibodies are created by RNA processing.

T cells - generation of a diverse T cell population depends upon the rearrangement of genes that comprise the variable region of the T-cell receptor

Question 31

Celled mediated immunity (Use Fig 7.16)

Answer 31

T cells

Principle fxn: destruction of microbes that are able to survive in the cytoplasm or phagocytic vesicles of infected cells

Can be harmful - responsible for the rejection of transplanted tissue and certain autoimmune diseases

For T cells to mount effector responses, they must first be stimulated through antigen recognition and then differentiate

Antigen-presenting cells (mostly dendrites) phagocytose antigens in the tissue and transport them to lymph nodes where they are presented to naive T cells via MHC molecules.

Upon activation of the T cell receptor/antigen recognition, *rapid proliferation of antigen-specific cells occurs

some naive T cells become effectors and kill the pathogen, some provide signals to other immune cells such as B cells to create antibodies, and some will become MEMORY t-cells

Question 32

T cell development

Answer 32

bone marrow to thymus gland to secondary lymphoid organs (lymph nodes and spleen)

While in the thymus, rearrangement of TCR genes occurs which determines the antigen specificity of the cells

Textbook info:

Positive selection in thymus:
- When CD4+ (helper cells) interacts with MHC class II, it receives positive selection signal to survive

• When CD8+ cells (cytotoxic cells) interacts with MHC class I, it receives positive selection signal to survive

Negative Selection: immunologic tolerance built
- negative selection deletes T cells that recognize “self” peptides of the host (when they bind TOO strongly to MHC of self), making the immune system nonreactive to its self

failure of negative selection = autoimmune diseases

Question 33

Immunologic memory

Answer 33

cell mediated immunity

when the host is re-exposed to an antigen, a secondary immune response is generated where memory T cells rapidly differentiate into effectors that can response more rapidly with heightened immune responses

basis for vaccination!

Question 34

Helper T cells

Answer 34

CD4+ cells

Fxns;
1. help B cells make antibodies
2. activate macrophages and help them destroy pathogens
3. helping CTLs proliferate and destroy virally infected cells
4. help NK cells kill infected cells
5. neutrophil recruitment
6. downregulation of adaptive immune response

HIV infection results in gradual decline of CD4 cells

Question 35

Cytotoxic T lymphocytes (CTLs)

Answer 35

Effector cells

Primarily CD8+ and thus class I restricted (recognize antigens presented by MHC class I molecules)

controlling viral infections by directly killing virally infected cells and producing cytokines that inhibit viral replication (IFNy)

Question 36

Regulatory T lymphocyte

Answer 36

prevent inappropriate responses against self antigens of the host or commensal microorganisms

Question 37

Humoral immunity

Answer 37

adaptive

anitbodies produced by B lymphocytes present in different body fluids or secretions such as saliva blood or vaginal secretions (very effective against organisms that are free floating in the body

Question 38

B cell development (slide says not to memorize process so whats the end result)

Answer 38

Develop in bone marrow and go to secondary lymph organs (spleen and lymph)

produce antibodies

Question 39

Main Phases of the immune system

Answer 39

recognition phase - innate receptors to pathogens or antibodies bound to invaders, adaptive immune recognition occurs

amplification phase - for innate: complement cascades, production of soluble factors and recruitment of army cells (neutrophils). For adaptive; proliferation of T and B cells and differentiation into effectors, replication into clones

effector phase - removal of antigens by multiple methods

termination phase - dampens the immune system after the antigen is cleared, crucial to prevent extra damage to host

memory - generation of long lived T and B cells (lower threshold so they react faster in future)

Question 40

Factors effecting immunity

Answer 40

aging - immune system less diverse, slower response

nutrition
- reduction of normal bacteria in gut after antibiotic treatment or bc infection may interfere with nutrients availability for immune fxn in Gi tract
- calorie, protein or vitamin A ane E deficiencies = T cell fxn deficencies and decreased amount
- zinc important for T and B
- obesity

environmental pollution and chemical exposure

trauma or illness

Question 41

How does exercise impact immune system

Answer 41

depends on intensity

regular and moderate = beneficial

strenuous, prolonged = impair

Question 42

Exercise effect on nuetrophils and macrophages

Answer 42

exercise triggers rise in blood levels of neutrophils and stimulates thier acitivty along with macrophages

exercise longer than 30min = rise in nuetrophils (PMNs) over next 2-4 hours

Question 43

Exercise effect on NK cells

Answer 43

number and fxn of NK cells increase during, and immediately after exercise

temporary and probably due to rise in epinephrine levels

after intense and long exercise, concentration and activity decreases below original values

Question 44

Exercise effect on inflammatory response

Answer 44

• brisk exercise = increased WBC count bc of increased cardiac output and epinephrine
• lymphocytes increase but decrease below normal levels after intense exercise
• strenuous or high intensity exercise can suppress immune fxn and damage enough tissue to provoke acute phase response
• regular exercise will protect against low grade inflammation

Question 45

How does exercise impact aging

Answer 45

exercise regulates the immune system and delays the onset of immunosenescence (decline of fxn from aging)

• enhanced vaccination response
• less tire T cells and inflammation
• increased t cell proliferation capacity and other immune cell activity
• longer leukocyte telomere lengths
• delays apoptosis

Question 46

Immune system and overtraining

Answer 46

can make you more susceptible to infection

neutrophils most altered with overtraining

intense exercise causes suppression of immune parameters in young people bu no huge effect on immune system of older adults (so relatively intense PA may be prescribed in elderly)

Question 47

Neck Check

Answer 47

if symptoms are above the neck exercise should be performed cautiously at half speed (if after 30 min symptoms are alleviated, continue, of they are worse, stop and rest)

if symptoms are below the neck or fever, exercise should not be initiated (aching muscles vomiting, hacking coach or diarrhea)