Lymphoid 1

Question 1

Types of innate immunity (2)

Answer 1

1) Physical and chemical barriers

2) Cells that destroy non-specifically

Question 2

Types of cells involved in non-specific innate immunity

Answer 2

1) Macrophages
2) Neutrophils
3) NK cells (natural killer)

Question 3

Three characteristics of acquired immunity

Answer 3

1) specificity
2) adaptive - will not respond until antigen is encountered
3) memory

Question 4

Two major functional types of lymphocytes

Answer 4

B cells

T Cells

Question 5

if a lymphocyte has never encountered its antigen then it has what three properties?

Answer 5

small
immunocompetent
naive

Question 6

B lymphocytes are responsible for what type of immunity? What do they do when activated?

Answer 6

humoral

turn into plasma cells for the secretion of antibodies

Question 7

name two classes of antibodies and a special feature of each

Answer 7

IgA - withstands mucosal environments

IgE - binds mast cell IgE receptor/antigen binding causes degranulation

Question 8

features of antibody structure

Answer 8

1) composed of a 2 heavy chains and 2 light chains
2) light chains are binding domains
3) base of “Y” is the Fc region for immune binding

Question 9

T-lymphocytes do what? (generally) what do they react to?

Answer 9

carry out cell mediated immunity

they react to cell bound antigen (not free antigen)

Question 10

types of T cells (3)

Answer 10

cytotoxic T cells - kill cells directly when receptor is bound (important for virus defense)
helper T cells - secrete paracrine cytokines
regulatory T cells - inhibit immune response with cytokines

Question 11

possible functions of helper T cells (3)

Answer 11

1) effector cells - recruit macrophages to generate immune inflammatory reactions
2) support cytotoxic T cell generation
3) promote activation of B cells and humoral immunity

Question 12

Phases of immune response

Answer 12

1) cognitive phase - recognition
2) activation phase
3) effector phase - clearance

Question 13

receptor composition on B cells and T cells

Answer 13

B cells express antibodies
T cells are more complex but still singularly specific and recognizes antigen bound in a particular way to cellular surfaces

Question 14

activation phase of immune response (generally)

Answer 14

effectors (T&B cells) are produced; takes place in lymphoid organs

Question 15

characteristics of APC cells (3)

Answer 15

1) presentation of the antigen to T cells by Antigen Presenting Cell (APC)
2) primarily dendritic cells; present in the epithelium but drain to lymphatics via lymphatic drainage (abundant in lymphoid tissue)
3) macrophages can serve as APC’s as well, though not as efficiently

Question 16

activation phase steps (5)

Answer 16

1) expansion of responsive cells by cloning those with the appropriate antibody (all steps are specific - only those with the appropriate antibody are produced)
2) activation of T cells by APC
3) activation of B cells by differentiation
4) Th cells activated to produce cytokines to positive feedback loop the creation of B cells and Tc cells
5) some progeny of B and T cells differentiate into memory cells

Question 17

what are the stages of the activation phase referenced via the activation of Th cells?

Answer 17

Naive Th gets activated by an antigen presenting cell (APC);
this activates the Th which then releases a set of cytokines that have three effects
1) activation of naive B cells into plasma cells to secrete antibodies
2) activation of Tc cells (that may have been exposed to the APC)
3) activation of inflammatory response

Question 18

what happens during the EFFECTOR phase?

Answer 18

clearance of the antigen; importantly, this occurs in the periphery

Question 19

what problems are posed by the SPECIFICITY of lymphocytes?

Answer 19

antigens can enter the system at any point, but there are not many circulating lymphocytes with that specific antibody attached;
therefore, bringing the appropriate lymphocyte/antibody combination together with its specific antigen (and all in the presence of an APC) can take time

Question 20

what are the two types of LYMPHOID ORGANS? what is the difference? examples of each?

Answer 20

primary - where naive B and T cells are manufactured - thymus and bone marrow
secondary - where the activation and effector phases are carried out; lymph nodes, spleen and mucosal lymphoid tissue

Question 21

characteristic composition of SECONDARY lymphoid tissue

Answer 21

1) many APC cells present to activate naive cells
2) antigens may get trapped here because these are locations for epithelial, blood and lymph filtration
3) lymphocyte recircultion - lymphocytes preferentially stay in these areas in order to maximize the chance that they will encounter the antigen that they are programmed to respond to

Question 22

what are the three types of lymphatic sinuses found in lymph nodes? what is the direction of flow and what are the vessels called?

Answer 22

(from inside out)
1) medullary sinus
2) intermediate (trabecular) sinus
3) subcapsular sinus
flow goes in the opposite direction (up this list), from an afferent vessel to the efferent vessel

Question 23

what types of cells can be found in the parafollicular (deep cortex) region? at the follicular (outer cortex) region? which is located closer to the hilum?

Answer 23

Parafollicular region contains T cells & APC cells, B cells can be found at the follicular region with some T cells. (PT Boat); the parafollicular region is closer to the hilum

Question 24

what provides ECM support for the stroma of secondary lymphoid organs? what functions does this network have? what provides support for the capsule and trabeculae?

Answer 24

reticular cells (type III collagen network); it provides the means for antigens to move across the node and produces factors important for organization of the node;
structural support for the capsule and trabeculae is provided by type I collagen

Question 25

what comprises a germinal center? color? type of cells located here (6)?

Answer 25

it is a pale-looking central area in a follicle (outer cortex) that is also called a secondary follicle. B cell activation is happening here but not complete maturation to plasma cells It is composed primary of cells that are undergoing differentiation, proliferation, apoptosis and macrophages that are digesting those cells that are undergoing apoptosis there are also non - APC dendritic cells in the germinal center; these are called follicular dendritic cells

Question 26

what's going on in the deep cortex? (Parafollicular area)

Answer 26

This is where T cells are activated | APC's accumulate here (cannot be distinguished from reticular cells without special stain)

Question 27

What are the two components of the medulla?

Answer 27

The sinuses and the cords

Question 28

What do you see inside the sinuses?

Answer 28

reticular cells, immature plasma cells and lymphocytes | lymph fluid

Question 29

What can be found inside the cords?

Answer 29

``` veins (arteries are located in the trabeculae) reticular cells macrophages lymphocytes plasma cells ```

Question 30

how is lymph flow altered to maximize presentation of antigens to lymphocytes?

Answer 30

lymph flow is baffled by reticular fiber network flow is allowed to pass through tissue or through the sinuses APCs carrying antigens are concentrated in the deep cortex, a denser area of the node macrophages accumulate at the entrance and exit of the node (subcapsular sinus and medullary cords)

Question 31

how do lymphocytes get into the node?

Answer 31

mostly through diapedesis through the blood vessels (esp. naive lymphocytes); specifically through the high endothelial venules (tall endothelial cells) in the post capillary venules (PCV) some delivered through the afferent lymph vessel

Question 32

where are the two main locations to find mucosal lymphoid tissue?

Answer 32

bronchial system and gut | tonsils, appendix and Peyer's patches in ileum

Question 33

what features of lymph nodes would you find in a mucosal lymphoid tissue? what specialized adaptation do they have? what does it do?

Answer 33

follicular and non-follicular areas, an efferent lymph duct; dendritic cells they have special M cells that are able to take up antigens from the "outside" environment