Ch. 17 Adaptive Immunity: Specific Defences of the Host

Question 1

characteristics of humoral and cellular immune systems

Answer 1

• acquired as a result of exposure to pathogens
• specific response developed for each different pathogen
• immunological memory

Question 2

it takes about ___ days from antigen exposure to produce antibodies in primary response

Answer 2

3

Question 3

secondary response

Answer 3

antibody titerlevel is adequate; could be years later. second exposure.

Question 4

naturally acquired immunity

Answer 4

infection; active or passive (mother–>baby).

body makes antibodies.

Question 5

artificially acquired immunity

Answer 5

antigens introduced in vaccine; passive (preformed antibodies in immune serum) or active (body makes antibodies)

Question 6

humoral immunity defends against…

Answer 6

freely circulatory pathogens (not intracellular)

Question 7

cellular immunity controls…

Answer 7

intracellular pathogens

Question 8

humoral effectors

Answer 8

antibodies (proteins)

Question 9

cellular effectors

Answer 9

T hlper cell, CT lymphocytes

Question 10

in humoral immunity, pluripotent stem cells…

Answer 10

after developoing in red bone marrow or fetal liver, they diverge into either B or T cells.

Question 11

to mature, B cells migrate to…

Answer 11

nowhere. they mature in red bone marrow in adults.

Question 12

to mature, T cells migrate to…

Answer 12

thyroid.

Question 13

after maturation, both B and T cells migrate to…

Answer 13

lymph nodes, spleen.

Question 14

B cell receptors

Answer 14

• antigen receptors have two binding sites, complementary in shape to a portion of antigens.
• Each different one has different receptors in term of shape (antigen) it can bind
• Shape is made as the B cell is made in the bone marrow

Question 15

Proliferation of B cells upon encountering specific antigens into … (2 types)

Answer 15

• Some proliferate into long-lived memory cells, which later can be stimulated to become antibody producing plasma cells.
• Others proliferate into antibody-producing plasma cells, which secrete antibodies into circulation.

Question 16

clonal selection

Answer 16

B cells with antigens attached are cloned.

Question 17

to become plasma cells, B cells need…

Answer 17

TH (helper) cells!

Question 18

antibodies

Answer 18

• Y shaped
• two antigen binding sites
• Complementary in shape to a bit of an antigen molecule called an epitope (antigenic determinant)
• Multiple antibodies to the various epitopes on the surface of one bacterial cell is a stronger reaction

Question 19

protective mechanisms of binding antibodies to antigens

Answer 19

(1) agglutination
(2) neutralisation
(3) activation of complement
(4) opsonization
(5) antibody-dependent cell-mediated cytotoxicity (ADCC)

Question 20

agglutination

Answer 20

reduces number of infectious units to be dealt with; bind different bacterial cells and clump them together

Question 21

neutralisation

Answer 21

Blocks adhesion of bacteria and viruses to mucosa; blocks attachment of toxin

Question 22

activation of complement

Answer 22

causes inflammation and cell lysis (activates classical pathway)

Question 23

opsonization

Answer 23

coating antigen with antibody enhances phagocytosis

Question 24

ADCC

Answer 24

• Antibodies attached to a target cell cause destruction by macrophages, eosinophils, and NK cells
• Perforin, lytic enzymes, etc cause pores in membrane very locally
• Needs antibodies binding to the epitopes; receptors on the surface of WBC (usually granulocyte)

Question 25

Types of T cells

Answer 25

- TH (CD4) - TC (CD8) - activated macrophages - natural killer (NK) cells - ADCC

Question 26

TH cell activation.

Answer 26

antigen presenting cell (APC -- usually dendritic cell) encounters and ingests a pathogen. Takes antigens and combines with MHC class II mol (one of your cells) and puts it on the surface. TH cells in the area bind to the complex, and this activates it! Costimulatory molecule from dendritic cell is also needed (so you don’t accidentally activate T cells) Secretes cytokines; signal other T cells and B cells to become activated Memory T cells also produced

Question 27

TC cell activation

Answer 27

``` same APC activation; however, shown on MHC class I cells; . T helper cells give cytokines and help activate. Activated cytotoxic T cells cause lethal hit by binding to abnormal cells (apoptosis); others differentiate into memory T cells. ```

Question 28

activated macrophages

Answer 28

Ruffling -- allows attachment to antigens | activation by cytokines from T cells, esp T helper

Question 29

natural killer cells and ... activation?

Answer 29

Kills virus infected cells Kill cancer cells Do not have to be activated like T cells do

Question 30

ADCC 2.0

Answer 30

Antibodies find antigens on the surface of a pathogen Variety of different WBC (NK, macrophages eosinophils) bind to other end of antibody (Fc region) Triggers WBC to release cytotoxic, lytic, and perforin enzymes Helps get rid of large, multicellular pathogens (e.g. helminths)