Antigens and The Major Histocompatibility Complex

Question 1

macromolecules capable of triggering an adaptive immune response by inducing the formation of antibodies or sensitized T cells in an immunocompetent host

Answer 1

immunogens

Question 2

a substance that reacts with antibody or sensitized T cells but may not be able to evoke an immune response

Answer 2

antigen

Question 3

T/F
all immunogens are antigens but not all antigens are immunogens

Answer 3

true

Question 4

Older individuals are more likely to have a decreased response to antigenic stimulation, neonates do not fully respond to immunogens, because their immune systems are not completely developed

Answer 4

age

Question 5

Individuals who are malnourished, fatigued, or stressed are less likely to mount a successful immune response

Answer 5

overall health

Question 6

A threshold dose, allows the innate immune response to take care of small amounts of pathogens and leave the adaptive response for pathogens that are present in large numbers

Answer 6

dose

Question 7

Include intravenous (into a vein), intradermal (into the skin), subcutaneous (beneath the skin), and oral administration

Answer 7

route of inoculation

Question 8

Linked to the MHC and to the receptors generated during T and B lymphocyte development

Answer 8

genetic capacity

Question 9

molecular weight of at least 10,000 to be recognized by the immune system, and the best immunogens typically have a molecular weight of over 100,000 daltons

Answer 9

macromolecular size

Question 10

______ is that the greater the molecular weight, the more potent the molecule is as an immunogen

Answer 10

the rule of thumb

Question 11

proteins and polysaccharides are the best immunogens (amino acids)

Answer 11

chemical composition and molecular complexity

Question 12

_______ recognize structures that project from the external surfaces of macromolecules

Answer 12

B cells

Question 13

_____ have epitopes that also stimulate T cells, which is essential to generating T-cell help in antibody production

Answer 13

proteins

Question 14

_______ are somewhat less immunogenic than protein

Answer 14

carbohydrates

Question 15

Carbohydrates are somewhat less immunogenic
than protein:

Answer 15

glycolipids or glycoproteins

Question 16

the A, B, and H blood group antigens are _______

Answer 16

glycolipids

Question 17

the Rh and Lewis antigens are _______

Answer 17

glycoproteins

Question 18

_______ and _______ are not immunogenic by themselves, although a response can be generated when they are attached to a suitable carrier molecule (DNA protein complex)

Answer 18

pure nucleic acids and lipids

Question 19

being able to distinguish between self and non-self, and those substances recognized as non-self are immunogenic

Answer 19

foreignness

Question 20

involves enzymatic digestion to create small peptides or pieces that can be complexed to MHC molecules to present to responsive lymphocytes

Answer 20

The ability to be processed and presented with MHC molecules

Question 21

Determinant site

Answer 21

epitope

Question 22

Molecular shapes or configurations that are recognized by B or T cells, may be repeating copies, or they may have differing specificities

Answer 22

epitope

Question 23

Linear or conformational

Answer 23

epitope

Question 24

surface antibody on B cells may react with both linear and conformational epitopes present on the surface of an immunogen

Answer 24

Epitope recognition by B cells

Question 25

T cells recognize an epitope only as a part of a complex formed with MHC proteins on the surface of an antigen-presenting cell

Answer 25

Epitope recognition by T cells

Question 26

Non-immunogenic materials that, when combined with a carrier, create new antigenic determinants

Answer 26

haptens

Question 27

May be complexed artificially with carrier molecules in a laboratory setting, or this may occur naturally within a host and set off an immune response

Answer 27

haptens

Question 28

Antigens that belong to the host

Answer 28

autoantigens

Question 29

These do not evoke an immune response under normal circumstances

Answer 29

autoantigens

Question 30

From other members of the host’s species

Answer 30

alloantigens

Question 31

Capable of eliciting an immune response

Answer 31

alloantigens

Question 32

They are important to consider in tissue transplantation and in blood transfusions

Answer 32

alloantigens

Question 33

From other species, such as other animals, plants, or microorganisms

Answer 33

heteroantigens

Question 34

Heteroantigens that exist in unrelated plants or animals but are either identical or closely related in structure so that antibody to one will cross-react with an antigen of the other

Answer 34

heterophile antigens

Question 35

A substance administered with an immunogen that increases the immune response; acts by producing a local inflammatory response that attracts a large number of immune system cells to the injection site

Answer 35

adjuvants

Question 36

______ are the only ones approved for clinical use in the United States, and these are used to complex with the immunogen to increase its size and to prevent a rapid escape from the tissues

Answer 36

aluminum salts

Question 37

aluminum salts must be injected into the ____ to work

Answer 37

muscle

Question 38

_____ is an example of using this type of adjuvant

Answer 38

hepatitis b vaccination

Question 39

______ are thought to enhance the immune response by prolonging the existence of immunogen in the area, increasing the effective size of the immunogen, and increasing the number of macrophages involved in antigen processing

Answer 39

adjuvants

Question 40

Formerly referred to as human leukocyte antigen (HLA)-Dausset

Answer 40

Major Histocompatibility Complex Molecules

Question 41

They determine whether transplanted tissue is histocompatible and thus accepted or recognized as foreign and rejected

Answer 41

Major Histocompatibility Complex Molecules

Question 42

Main function is to bring antigen to the cell surface for recognition by T cells, because T-cell activation will occur only when antigen is combined with MHC molecules

Answer 42

major histocompatibility complex molecules

Question 43

They are relevant, because they may be involved in transfusion reactions, graft rejection, and autoimmune diseases

Answer 43

major histocompatibility complex molecules

Question 44

Genes controlling expression of these molecules are actually a system of genes known as the _______

Answer 44

major histocompatibility complex (MHC)

Question 45

Genes coding for the MHC molecules in humans are found on the ______ and are divided into three categories or classes

Answer 45

short arm of chromosome 6

Question 46

______ are coded for at three different locations or loci, termed A, B, and C

Answer 46

class I molecules

Question 47

_____ are situated in the D region, and there are several different loci known as DR, DQ, and DP

Answer 47

class II genes

Question 48

There is a gene that codes for the alpha chain and one or more genes that code for the beta chain

Answer 48

class II genes

Question 49

______ coded between the class I and class II regions on chromosome, codes for complement proteins and cytokines such as tumor necrosis factor

Answer 49

class III

Question 50

Expressed on all nucleated cells

Answer 50

class I

Question 51

Highest on lymphocytes and low or undetected on liver hepatocytes, neural cells, muscle cells, and sperm

Answer 51

class I

Question 52

Class I: The alpha chain has a molecular weight of ______

Answer 52

45,000

Question 53

A lighter chain associated with it, called a ______, has a molecular weight of ______ (alpha chain domains – a1, a2, a3)

Answer 53

beta2-microglobulin 12,000

Question 54

reacts with CD8 on cytotoxic T cells

Answer 54

a3

Question 55

Found primarily on antigen-presenting cells, which include B lymphocytes, monocytes, macrophages, and dendritic cells

Answer 55

class II

Question 56

___ is expressed at the highest level, as it accounts for about one-half of all the class II molecules on a particular cell

Answer 56

DR

Question 57

_____ is the most highly polymorphic, as 18 different alleles are known at this time

Answer 57

DR gene

Question 58

Both the chain, with a molecular weight of 33,000, and the chain, with a molecular weight of 27,000, are anchored to the cell membrane

Answer 58

class II

Question 59

To bind peptides within cells and transport them to the plasma membrane, where T cells can recognize them in the phenomenon known as antigen presentation

Answer 59

Role of MHC Class I and II

Question 60

Mainly present peptides that have been synthesized within the cell to CD8 (cytotoxic) T cells

Answer 60

class I

Question 61

The watchdogs of viral, tumor, and certain parasitic antigens that are synthesized within the cell

Answer 61

class I

Question 62

Display of hundreds of class I molecules complexed to antigen allows CD8+T cells to continuously check cell surfaces for the presence of non-self-antigens

Answer 62

class I

Question 63

If it recognizes an antigen as being foreign, the CD8+T cell produces _____ that causes lysis of the entire cell

Answer 63

cytokines

Question 64

Present antigen to CD4 (helper) T cells

Answer 64

class II

Question 65

Mainly bind exogenous proteins – those taken into the cell from the outside and degraded

Answer 65

class II

Question 66

Stimulate CD4 T cells in the case of bacterial infections or the presence of other material that is endocytosed by the cell

Answer 66

class II

Question 67

On the cell surface, ______ are responsible for forming a trimolecular complex that occurs between antigen, class II molecule, and an appropriate T-cell receptor

Answer 67

class II molecules

Question 68

If binding occurs with a T-cell receptor on a CD4+T cell, the T helper cell recruits and triggers a B-cell response resulting in _____

Answer 68

antibody formation