Chapter 8 Adaptive Immunity

Question 1

Two main types of lymphocytes

Answer 1

B cells (mature in bone marrow) T cells (mature in thymus)

Question 2

Two main types of adaptive immunity

Answer 2

Humoral immune responses and cell mediated immune responses.

Question 3

Humoral immunity

Answer 3

The component of the immune system involving antibodies that are secreted by B cells and circulate as soluble proteins in blood plasma and lymph.

Question 4

Cell-mediated immunity

Answer 4

immunity conferred to an individual through the activity of T cells, involving the direct destruction of viruses, foreign particles, etc. Involves cytotoxic T-cells and Helper T-cells.

Question 5

Adaptive immunity

Answer 5

Is the body’s ability to recognize and defend itself against distinct invaders and their products.

Question 6

5 attributes of adaptive immunity

Answer 6

1) Specificity
2) Inducibilty (only acting when you need it)
3) Clonality (clonal selection theory)
4) Unresponsiveness to self (tolerance)
5) Memory (very important regarding vaccination)

Question 7

Lymphatic System

Answer 7

Screen tissues of the body for foreign antigens. Composed of lymphatic vessels and cells, tissues, and organs.

Question 8

Lymphatic vessels and the flow of lymph

Answer 8

One-way system that conducts lymph from tissues and returns it to the circulatory system via left subclavian vein.

Question 9

Lymph

Answer 9

Liquid with similar composition to blood plasma. Arises form fluid leaked form vessels into surrounding tissues.

Question 10

Primary (central) lymphoid organs

Answer 10

Where cells undergo maturation. Red bone marrow and thymus.

Question 11

Secondary lymphoid organs

Answer 11

Where matured cells reside and function. Lymph nodes, spleen, tonsils, mucosa-associated lymphatic tissue (MALT)

Question 12

Lymph nodes

Answer 12

Are small bean shaped structures in the body that carry lymph fluid, nutrients, and waste material between the body tissues and the bloodstream.

Question 13

Antigens

Answer 13

Molecules the body recognizes as foreign and worthy to attack. Provoke a specific immune response. Recognized by three-dimensional regions called epitomes. Food and dust can be considered antigenic particles.

Question 14

Exogenous antigens

Answer 14

Are antigens that have entered the body from the outside, for example by inhalation, ingestion, or injection.

Question 15

Endogenous antigens

Answer 15

Are antigens that have been generated within previously-normal cells as a result of normal cell metabolism, or because of viral or intracellular bacterial infection.

Question 16

Autoantigen

Answer 16

Is usually a normal protein or complex of viral or intracellular bacterial infection.

Question 17

B Lymphocytes (B cells) and antibodies

Answer 17

Arise and mature in the bone marrow. Found primarily in the spleen, lymph nodes, and MALT. Small % of B cells circulate in the blood. Major function is the secretion of antibodies.

Question 18

Specificity of the B cell receptor (BCR)

Answer 18

Each B cell has multiple copies of the B cell receptor. Each B cell generates a single BCR. Two variable regions of the BCR form the antigen binding sites. Each BCR only recognizes only one epitope. The entire repertoire of an individuals BCRs is capable of recognizing millions of different epitopes.

Question 19

Specificity and Antibody structure of B cells

Answer 19

Antibodies are immunoglobulins similar to BCRs. Secreted by activated B cells called plasma cells. Have identical antigen-binding sites and antigen specificity as the BCR of the activated B cell.

Question 20

Antibody function

Answer 20

Antigen-binding sites are complementary to epitomes. Antibodies function is several ways:

1) Neutralization
2) Opsonization
3) Killing by oxidation
4) Agglutination
5) Activation of complement & inflammation

Question 21

Classes of antibodies

Answer 21

Class involved in the immune response depends on the type of antigen, portal entry, and antibody function needed. 5 classes IgM, IgG, IgA, IgE, IgD

Question 22

IgM

Answer 22

First antibody produced (pentameric)–> Primary response

Question 23

IgG

Answer 23

Most common and longest-lasting antibody (memory response)

Question 24

IgA

Answer 24

Associated with body secretions (dimeric)

Question 25

IgE

Answer 25

Involved in response to parasitic infections and allergies.

Question 26

IgD

Answer 26

Function unknown

Question 27

T Lymphocytes (T cells)

Answer 27

Produced in bone marrow and matures in Thymus. Circulates in lymph and blood and migrates to the lymph nodes, spleen and Peyer’s Patches. Antigen binding sites are complementary to epitomes. Have T-cell receptors on their cytoplasmic membrane.

Question 28

Specificity of the T cell receptor

Answer 28

TCRs do not recognize epitomes directly. TCRs only bind epitopes associated with a MHC protein. TCRs act primarily against cells that harbor intracellular pathogens. TCR cannot get secreted (BCR can)

Question 29

Epitopes

Answer 29

A localized region on the surface of an antigen that is capable of eliciting an immune response and of combining with a specific antibody to counter that response.

Question 30

Types of T lymphocytes

Answer 30

Are based on surface glycoproteins and characteristic functions. Three types: Cytotoxic T lymphocyte (CD8+), Helper T lymphocyte (CD4+), Regulatory T lymphocyte.

Question 31

Cytotoxic (CD8) T cells

Answer 31

Directly kills other cells (virally infected)

Question 32

Helper (CD4) T cells

Answer 32

Helps regulate the activities of B cells (Th2) and cytotoxic T cells (Th1)

Question 33

Regulatory T lymphocyte

Answer 33

Represses adaptive immune responses

Question 34

Clonal deletion of auto-reactive B cells

Answer 34

It is vital that immune responses not be directed against autoantigen. Body eliminates self-reactive lymphocytes. The immature B cells whose BCRs bind too strongly to self antigens will not be allowed to mature. If B cells are found to be highly reactive to self they are induced to undergo apoptosis. This happens in the bone marrow for B cells.

Question 35

Clonal deletion of auto-reactive T cells in the Thymus

Answer 35

During their maturation in the thymus, lymphocytes that react to autoantigens are eliminated by being induced to undergo apoptosis.

Question 36

Thymocyte TCR generation deletion of auto reactive cells

Answer 36

Functional (positive) selection and Autoreactive (negative selection).

Question 37

Functional (positive) Selection

Answer 37

Thymocytes generate TCR as well as CD4 and CD8. Receptors interact with MHC and HLA antigens to select for correctly assemble receptors.
Positive selection eliminates weakly binding cells by apoptosis. Only high-binding cells (TCR binding to MHC I/II or peptide) are selected.

Question 38

Autoreactive (negative selection)

Answer 38

Thymocytes in the medulla undergo selection against TCR reactivity with auto-antigens. Autoreactive cells are deleted by apoptosis. There is some clonal amplification and cells become single-positive (i.e., either expressing CD4 (Th) or CD8 (CTL).

Question 39

Cytokines

Answer 39

Cells of immune system communicate by releasing soluble regulatory proteins that act on other cells. Cytokines secreted by various leukocytes. The complex web of signals among all the cells of the immune system is called the cytokine network. The cell receives the information from cytokine-activated receptor to produce another messenger.

Question 40

Interleukins (ILs)

Answer 40

Signal among leukocytes and other tissues.

Question 41

Interferons (IFNs)

Answer 41

Antiviral proteins that may act as cytokines.

Question 42

Growth factors

Answer 42

Proteins that stimulate stem cells to divide

Question 43

Tumor necrosis factor (TNF)

Answer 43

Secreted by macrophages and T cells to kill tumor cells and regulate immune responses and inflammation.

Question 44

Chemokines

Answer 44

Chemotactic cytokines that signal leukocytes to move.

Question 45

Roles of MHC

Answer 45

Group of antigens first identified in graft patients. Important in determining compatibility of tissues for tissue grafting. MHC antigens are glycoproteins found in the membranes of most cells of vertebrate animals. Hold and position antigenic determinates for presentation to T cells. Antigens bind in the antigen-binding groove of MHC molecules.