Immune System II

Question 1

_____ are immunocompetent (mature) lymphocytes created during an infection. They
remain alive long after the infection, allowing the body to “remember” the antigen and
react quickly if it returns.

Answer 1

Memory cells

Question 2

Memory cells express _____ that was expressed by the parent lymphocyte.

Answer 2

the same antigen receptor

Question 3

For the body to mount a specific defense against a newly encountered invader takes
_____ . (There may be only a single lymphocyte in the body that happens to
bind to it!)

Answer 3

days or weeks

Question 4

The response to a newly encountered invader is called the _____.

Answer 4

primary immune response

Question 5

Re-exposure, even years later, to an antigen that has been responded to before results in
a specific defense that takes _____ to mount. This is due to the presence of _____.
(There are thus many lymphocytes in the body that are able to bind to the antigen.)

Answer 5

only hours; memory cells

Question 6

The response to an invader that has been attacked in the past is called the _____.

Answer 6

secondary immune response

Question 7

Once a lymphocyte is capable of binding to a specific antigen, it is said to be _____ or
_____.

Answer 7

mature; immunocompetent

Question 8

Immunocompetent lymphocytes have a set of _____ on their surface which can bind to a
specific antigen.

Answer 8

receptors

Question 9

The antigen binding receptors of lymphocytes are produced by the _____ that produce
them, so that the number that can be made by a single person is very large.

Answer 9

shuffling of portions of the

genes

Question 10

. Immature lymphocytes are formed from hematopoietic stem cells in the _____.

Answer 10

bone marrow

Question 11

Each immature lymphocyte displays _____, but most such cells are unwanted.

Answer 11

a single antigen-binding

receptor

Question 12

Lymphocytes whose antigen receptors do NOT react with ‘self’ cells are said to be _____,
but many immature lymphocytes do not meet this standard.

Answer 12

tolerant

Question 13

Most B-cells whose receptors bind to “self” proteins are destroyed in _____.

Answer 13

the bone marrow

Question 14

In the thymic cortex, immature T-cells that _____ are allowed to survive until the next
stage: those that can’t, die. (+ binding = live) This is called _____ selection.

Answer 14

recognize “self” MHC proteins;

positive

Question 15

In the thymic medulla, immature T-cells whose antigenic receptor binds to _____ are killed
(- binding = live). This is called _____ selection.

Answer 15

“self” proteins displayed by the

MHC; negative

Question 16

The acquired immune response can be divided into two branches: the _____ response
recognizes antigens or pathogens that are not associated with any “self” cells.

Answer 16

humoral

Question 17

The acquired immune response can be divided into two branches: the _____ response
recognizes antigens that are associated with “self” cells (such as virally infected cells, or
antigen presenting cells).

Answer 17

cell-mediated

Question 18

Humoral immunity is mediated by _____ produced by plasma cells present in the body’s
“humors” or fluids.

Answer 18

antibodies

Question 19

B-cells recognize antigens that are _____: that is, that are not displayed as part of a MHC

Answer 19

free in the body

Question 20

The first response in the humoral branch of the immune response is _____.

Answer 20

the binding of a B-cell to an

antigen

Question 21

When a B-cell encounters an antigen and has been activated, it proliferates into two types
of cells: _____ and _____.

Answer 21

plasma cells; memory cells

Question 22

Plasma cells produce antibodies that can bind to _____.

Answer 22

the same antigen that was

recognized by the parent B cell

Question 23

Antibodies are produced by _____ in the lymph.

Answer 23

plasma cells

Question 24

Antibodies are _____, each of which can bind to _____ identical antigens.

Answer 24

proteins; two or more

Question 25

Most antibodies are essentially Y-shaped: the stem of the Y is _____ and the branches of the Y are _____ and are called the _____.

Answer 25

constant; variable; variable | region

Question 26

It is the differences in the _____ that enables different antibodies to bind to different antigens.

Answer 26

variable region

Question 27

``` _____ refers to the fact that antibodies “get in the way,” so to speak, interfering with the function of the proteins or cells to which they bind. ```

Answer 27

Neutralization

Question 28

_____ refers to the fact that, since each antibody can bind to two antigen molecules, they can cause the antigen (or cells which display it) to clump. This makes them vulnerable to _____.

Answer 28

Agglutination; the non-specific | immune system

Question 29

Elements of the non-specific immune system, including macrophages and complement proteins, recognize antibodies in the body which _____. This results in the destruction of the antigen.

Answer 29

have bound to an antigen

Question 30

Although Y shaped, compared to fibrous proteins, antibodies are round or globe shaped. Thus, antibodies are called the _____.

Answer 30

immunoglobulins (Ig)

Question 31

Antibodies are divided into five classes based on their structure: _____, _____, _____, _____ and _____.

Answer 31

IgA; IgD; IgE; IgG; IgM

Question 32

Most _____ is found as a dimer (two stuck together) in body secretions, and helps to _____.

Answer 32

IgA; prevent pathogens from | attaching to the body’s surface

Question 33

_____ serves as an antigen receptor for B-cells: it is physically attached to their surface.

Answer 33

IgD

Question 34

_____ is found in barrier regions, bound to mast cells and basophils: antigen binding causes the cells to _____.

Answer 34

IgE; release histamine and | other inflammatory chemicals

Question 35

Most antibodies are _____. When bound to an antigen, these are recognized by other components of the immune system, which then _____.

Answer 35

IgG; destroy the object to which | it is bound

Question 36

The monomer form of _____, like IgD, serves as an antigen receptor for B-cells.

Answer 36

IgM

Question 37

As a pentamer (five units bound together), _____ is the first antibody released by new plasma cells and so can serve as a marker for an active infection.

Answer 37

IgM

Question 38

Like IgG, when bound to an antigen, the pentameric form of _____ is recognized by other components of the immune system which destroy the object to which it is bound.

Answer 38

IgM

Question 39

_____ is mediated by T lymphocytes which respond only to living cells which display both _____ and _____.

Answer 39

Cell mediated immunity; foreign | antigens; “self” (MHC) proteins

Question 40

When T-cells bind to a non-self cell and are activated, they proliferate, leading to the production of _____, _____, _____ and _____ T cells.

Answer 40

killer; helper; suppressor; | memor

Question 41

Killer T-cells are also called _____ cells or _____ cells.

Answer 41

cytotoxic T; CD8

Question 42

Killer T-cells recognize MHCI proteins mixed with antigens, and respond by _____.

Answer 42

producing toxins which cause | the infected cells to die

Question 43

Helper T-cells are also called _____ cells, because of the major receptor they express on their surface.

Answer 43

CD4

Question 44

The function of helper T-cells is to stimulate B-cells to _____, and to stimulate both B-cells and T-cells to _____. (That is, they produce co-stimulators.)

Answer 44

produce antibodies; divide

Question 45

. Without _____ there can be no adaptive immune response.

Answer 45

helper T-cells

Question 46

``` An interleukin is a type of cytokine which is released by _____ and allows communication between leukocytes (inter-leukocyte communication). Interleukin is a co-stimulator and activates _____. ```

Answer 46

helper T-cells and APCs; | antigen-bound lymphocytes

Question 47

_____ are needed at the end of an infection to shut down the immune response.

Answer 47

Suppressor T-cells

Question 48

_____ are the most similar to the parent T-cell: they remain in circulation long after the infection is over, ready to recognize the pathogen if it returns.

Answer 48

Memory T-cells

Question 49

One way that we medically supplement the immune response is to directly kill the pathogen (if it is bacterial or eukaryotic) by the use of _____.

Answer 49

antibiotics

Question 50

One way that we medically supplement the immune response is to inject _____ that are _____ the pathogen, so that the body will recognize it in the future. (This is called vaccination.)

Answer 50

harmless antigens; derived in | some way from

Question 51

One way that we medically supplement the immune response is to directly transfer antibodies from one individual to another: this confers _____.

Answer 51

passive immunity

Question 52

The immunity created by our own immune system is called _____.

Answer 52

active immunity

Question 53

Newborn infants have passive immunity to many pathogens due to _____.

Answer 53

transfer of maternal antibodies | through the placenta

Question 54

Transplant success depends on the similarity of the tissues because cytotoxic T-cells, NK cells, and antibodies work to _____.

Answer 54

destroy non-self tissues

Question 55

Autografts are tissue grafts transplanted from _____.

Answer 55

one body site to another in the | same person

Question 56

Allografts are grafts transplanted from _____. Currently, to be successful, the immune system must be suppressed.

Answer 56

individuals that are not genetically identical but belong to the same species

Question 57

Xenografts are grafts _____. Currently, to be successful, the immune system must be suppressed.

Answer 57

taken from another animal | species

Question 58

_____ are any congenital or acquired conditions that cause immune cells, phagocytes, or complement to behave abnormally.

Answer 58

Immunodeficiencies

Question 59

Severe combined immunodeficiency (SCID) is a congenital condition that produces a deficit of _____.

Answer 59

lymphocytes

Question 60

Acquired immune deficiency syndrome (AIDS) cripples the immune system by interfering with _____.

Answer 60

helper T-cells

Question 61

_____ occur when the immune system loses its ability to differentiate between self and non-self. As a result, the body _____.

Answer 61

Autoimmune diseases; attacks | its own cells

Question 62

Hypersensitivities, or allergies, are the result of the immune system causing tissue damage as it attacks _____.

Answer 62

a harmless substance