Lecture 17 Flashcards Preview

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Flashcards in Lecture 17 Deck (49):
1

How many major HLA genes are needed for most transplants to succeed?

4

2

HLA genes

account for about 50% of the genetic impact on immunity

3

what determines an HLA type

several genes with multiple alleles

4

Major histocompatibilty complex

MHC region on short arm of chromosome 6 containing about 70 genes

5

what encodes human leukocyte antigens (hla)

MHC class I and II

6

what is the difference between class I and II HLAs that encode human leukocyte antigens?

Class I - encode antigens defining "self"
Class II - encodes several proteins found in antigen-presenting cells

7

MHC class III genes

encode protein providing non-specific immune functions

8

the human immune system

a network of vessels called lymphatics and bean-shaped structures called lymph notes

9

what is lymph and what does it carry

the fluid filling the lyph ducts
-carries macrhopages and B- and T- lymphocytes

10

what organs are involved in production or maturation of immune cells

spleen and thymus
bone marrow

11

immunity

the immune response attacks pathogens, cancer cells and transplanted cells with two lines of defense
1) innate immunity
2) adaptive immunity

12

difference between innate and adaptive immunity

-innate immunity - immediate and generalized
-adaptive immunity - specific and slower

these act after various physical barriers block pathogens

13

physical barriers

The first line of defense
Examples include:
- Unbroken skin
- Mucous membranes and secretions
- Waving cilia of the respiratory
tract
- Flushing effect of tears, saliva,
urination, and diarrhea
All of these are non-specific defenses

14

a central part of innate immune response - inflammation

- A process that creates a hostile
environment for pathogens
- Sends in phagocytes that engulf and destroy pathogens via phagocytosis

15

innate immune response

OInflammation
Collectins
- Recognize specific bacterial
antigens
Cytokines
- Interferon = Anti-viral
- Interleukins = Fever-inducing
- Tumor necrosis factor α = Anticancer

Cytokines also play a role in adaptive immunity

16

what immunity do cytokine play a role in?

adaptive and innate immunity

17

complement system (innate immune response)

- Plasma proteins that assist or
complement other defense responses
- Roles of complement proteins
include:
Puncture bacterial cells Dismantle viruses
Trigger histamine release to
dilate blood vessels
Attract phagocytes

18

adaptive immunity

Requires stimulation
Response time is in days
Has three basic characteristics:
1) Diversity: many different pathogens
recognized.
2) Specificity: distinguishes particular molecules.
3) Memory: responds faster with
subsequent exposure.
- Primary immune response: reaction to first exposure.
- Secondary immune response: reaction to exposure using “memory” of first response.

19

adaptive immunity - two types of response

1)Humoral immune response
- B cells produce antibodies in
response to activation by T cells

2)Cellular immune response
- T cells produce cytokines and
activate other cells

20

cytokines

- Interferon = Anti-viral
- Interleukins = Fever-inducing
- Tumor necrosis factor α = Anticancer

21

humoral immune response

1. Antigen-presenting macrophage activates a helper T cell
2. Helper T cell activates a B cell with matching cell surface receptors
3. B cells divide to produce plasma cells and memory cells
4. Plasma cells secrete antibodies into blood that will recognize the antigen presented.
5. Memory cells remain dormant until second exposure when they respond faster and more effectively

22

humoral immune response - polylonal

polyclonal
-different antibody proteins recognize and bind to different features of foreign cells

23

antibody structure

Minimally consist of four polypeptide chains
- Two long (heavy) chains
- Two shorter (light) chains
-Constant region of each chain is similar
-Variable region of each chain is diverse

24

Antigen binding sites

-Idiotypes: sites in direct contact with antigen
-Epitope: portion of the antigen contacting the antibody

25

large antibody molecules

consist of two or five Y-shaped subunits

26

function of antibodies

-Bind pathogen protein or toxin and inactivates or neutralizes them
-Can clump pathogens making them more visible for macrophages
-Activate the complement system boosting the innate immune response

In some situations, the antibody
response can be harmful

27

another word for antibodies

immunoglobulines
-five major types distinguised by location and function

28

creation of antibody diversity

-During early development of B cells, sections of the antibody genes are rearranged along their chromosome
-Rearrangement due to enzymes cutting and pasting different combinations of V (Variable), D (Diversity), and J (Joining) genes creates new versions of the antibody proteins

29

genes and chains on the chromosomes

-V, D and J genes for heavy chains are on chromosome 14.
-V and J genes for light chains are on chromosomes 2 and 22.

30

cellular immune response maturation of T cells

-T cells must recognize foreign antigens and not recognize self antigens
-Immature T cells, called thymocytes, travel to the thymus and display their cell surface receptors
-The thymus lining displays self antigens
-T cells that bind these self antigens die by apoptosis
-T cells that do not bind the self antigens survive and mature

31

Thymocytes

immature T cells that travel to the thymus and display their cell surface receptors

32

what happens when T cells bind to self antiens

T cells must recognize foreign antigens and not self antigens because T cells that bind to self antigens die by apoptosis
-T cells that do not bind the self antigens survive and mature

33

Types of T cells

- Helper T cells - Have CD4 antigens
- Cytotoxic T cells - Have CD8 antigens
- Regulatory T cells - Secrete cytokines

34

Role of T cells in humoral immune response

- Recognize antigens presented by macrophages
- Helper T cells stimulate B cells to produce antibodies

35

Role of T cells in cellular immune response

- Secrete cytokines
- Activate cytotoxic T cell

36

types of cytokines - colony stimulating factors

stimulate bone marrow to produce lymphocytes

37

types of cytokines - interferons

block viral replication, stimulate macrophage to engulf viruses, stimulate B cells to produce antibodies, attack cancer cells

38

types of cytokines - interleukins

contol lymphocyte differentiation and growth, cause fever that accompanies bacterial infection

39

types of cytokines - tumor necrosis factor

stop tumor growth, releases growth factors, stimulates lymphocyte differentiation, dismantles bacterial toxins

40

cytotoxic T cells

Continuously monitor body cells, recognizing and eliminating virus-infected and tumor cells

41

abnormal immunity

immunity may be too weak,
too strong, or misdirected

Abnormal immune responses may be multifactorial or caused by a mutation in a single gene

42

inherited immune deficiencies

At least 20 types
Affect innate and adaptive immunity

Examples
- Chronic granulomatous disease:
Mutation of oxidase enzyme results in neutrophils that cannot kill bacteria
- Severe combined immune deficiency (SCID): Impacts both humoral and cellular immunity due to lack of mature B cells and/or T cells

43

immune system cells - macrophages

presents antigens
performs phagocytosis

44

immune system cells - mast cell

releases histamine in inflammation
releases allergy mediators

45

immune system cells - b cell

matures into antibody producing plasma cell or into memory cell

46

immune system cells - helper t cells

-recognizes nonself antigens presentd on macrophages
-stimulates B cells to produce antibodies
-secretes cytokines
-activates cytotoxic T cells

47

immune system cells - cytotoxic

attacks cancer cells and cells infected with viruses upon recognizing antigens

48

immune system cells - natural killer

attacks cancer cells and cells infected with viruses without recognizing antigen; activates other white blood cells

49

immune system cells - suppressor

inhibits antibody production