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Semester 2 Immunology > Immunology I > Flashcards

Immunology I Flashcards

1
Q

What are the functions of immunology?

A

Many functions:
Protection from microbial pathogens
Protection from “foreign” cells that may have malignant potential
Detects damaged tissue and facilitates regeneration or repair of those tissues
Permits microflora to aid in
Protection
Provision of nutrients

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2
Q

What are the components of immunology?

A

A wide diversity of cells derived from the bone marrow and that are relatively free to circulate through the body
Discrete, unique and widely-distributed lymphatic tissues
A wide diversity of molecular signals and effectors that are relatively free to circulate throughout the body

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3
Q

What are some immunological disorders?

A

Allergy and autoimmune disease (immune-mediated diseases)
Acute and chronic inflammatory states (outside of immune-mediated diseases)
“Bystander” damage that happens when attacking a pathogen

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4
Q

Overview of the immune response. 3 steps

A

Most components of the immune system contribute to:

1.) Recognizing foreign molecules, microbes, or cells

2.) Destroying foreign molecules, microbes, or cells
Often by disrupting cell membranes, using free radicals to damage cellular components, or enzymatically catalyzing degradation of cellular components
That which cannot be destroyed is often isolated from the rest of the body

3.) Communicating between these two activities

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5
Q

Immune system has 2 major functional divisions, what are they?

A

1.) Innate immunity - “1st line of defense”

2.) Adaptive immunity - activated when innate defenses are breached (delayed)

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6
Q

What are the cellular and molecular features of innate immunity vs. adaptive immunity?

A

Innate immunity - “1st line of defense”
Features cellular and molecular effectors that are either:
Less specific – each cell or molecule recognizes a range of targets
Genetically “hard-wired” – cells and molecular effectors don’t change during the lifespan of the organism

Adaptive immunity - activated when innate defenses are breached (delayed)
Features cellular and molecular effectors that are:
Highly specific – each cell or molecule recognizes a particular target
Genetically “changeable” – cells and molecular effectors change their germline DNA to produce unique receptors/effectors during the lifespan of the organism

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7
Q

Adaptive vs. innate immune response chart

A
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8
Q

What is the specificity of adaptive immunity?

A

Specificity:
Recognition of a foreign molecule by high-affinity binding to a receptor
The affinity can increase as the receptor is modified over time
Receptors are generated by genetic recombination (gene shuffling) particular portions of the receptor

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9
Q

What is an antigen?

A

A substance that can bind to a receptor of the adaptive immune system
Receptors include B-cell and T-cell receptors
B-cell receptors can be released from a B-cell into the ECF  antibody

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10
Q

What is an immunogen?

A

A substance that can generate an adaptive immune response

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11
Q

What is an epitope?

A

The molecular entity that binds to the receptor
This antigen displays multiple different epitopes – note the different antibody affinities
These were all produced by different B-lymphocytes

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12
Q

What is a hapten?

A

A substance that can bind to an antibody, but CANNOT generate an immune response
Often haptens are “too small” to activate the receptor

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13
Q

How many distinct antigens can the vertebrate immune system recognize? How is this accomplished?

A

~10^16

This is accomplished by sets of corresponding recognition molecules (receptors) on immune cells
B cell receptors (antibodies)
T cell receptors

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14
Q

True or False. No two naïve T or B cells are activated by the same molecule

A

True

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15
Q

Diversity is accomplished by randomly “shuffling” portions of genes for lymphocyte receptors and selecting receptors that are what 2 things?

A

1.) Functional
2.) Do not recognize self

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16
Q

What is a lymphocyte receptor repertoire?

A

the set of antigen (Ag) receptors in a given individual’s immune system

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17
Q

**In adaptive immunity, what is clonal selection theory?

A

Each lymphocyte bears a single type of receptor with a unique specificity
Receptor binding is required for cell activation
The differentiatedeffector cellsderived from an activated lymphocyte bear receptors of identical specificity as the parent cell
They are clones of the parent cell – exact genetic copies with the same receptor
Those lymphocytes bearing receptors for self molecules (i.e.,endogenousantigens produced within the body) are destroyed at an early stage
We select functional receptors that do not bind to self

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18
Q

In adaptive immunity, what is a B cell receptor?

A

Naïve B cells express Ab on their surface, where they are called B cell receptors
Once activated, B cells secrete Abs into the blood (aka Immunoglobulins – Igs)

Light chains (2) and heavy chain (2)—each with variable and constant regions
The variable regions are the portions that are “shuffled” and that can bind to antigen
Some antigens can be bound by many different antibodies
Different epitopes on the same antigen

Most antibodies bind to protein antigens – distinct sequences of amino acids
Recognized amino acid sequence can be either
Continuous (aka linear), or
Discontinuous (aka conformational)

Antibodies can also bind to lipid, nucleic acid, and carbohydrate moieties
A wide range of molecules can be recognized

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19
Q

In adaptive immunity, what are characteristics of T cell receptors?

A

Structurally very similar to the Fab portion of an Ab
2 chains: 1 alpha, 1 beta—each with a variable (V) region and a constant (C) region
Best at recognizing protein antigens
The T-cell receptor is never secreted – it always stays attached to the membrane

T-cell receptors only recognize antigen by close communication with molecules on other cells
This is known as antigen presentation
Complicated interaction that we will delve into later – T-cell receptors never bind to antigen “just floating around” dissolved in the ECF

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20
Q

T or F. Secondary immune responses are generally:
Faster
Larger
Qualitatively different and often involve relatively high-affinity B-cell receptors

A

True

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21
Q

Exposure of the adaptive immune system to an antigen (increases or decreases) its ability to respond to the same or closely related antigen following re-exposure

A

increases

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22
Q

T or F. Both adaptive and innate immune responses are transient

A

True

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23
Q

Can the innate and adaptive immune systems interact?

A

Yes

24
Q

Which immune system is more tightly regulated and controlled?

A

adaptive

25
Q

Immune responses to self can result in ___________
Immunological unresponsiveness to self = ___________

A

autoimmunity, tolerance

26
Q

A cell that has not reached a point where it can become activated – usually refers to cells of the adaptive immune system

A

Immature

27
Q

A mature cell that has not yet been activated – always refers to the adaptive immune system

A

Naive

28
Q

A cell (or group of cells) that is currently an active participant in an immune response

A

Activated or effector

29
Q

A cell that responds to receptor binding by deactivation of the cell – it “goes to sleep”

A

Anergic

30
Q

A group of effector T/B cells that express the same antigen receptor and are derived from the same parent cell

A

Clone

31
Q

What is a collection of cells, chemicals and processes that function to protect the skin, respiratory passages, intestinal tract and other areas from foreign antigens?

A

The immune system

32
Q

What are 2 cells and 2 tissues of the immune system?

A

Myeloid Cells
Lymphoid Cells
Primary Lymphoid Tissue
Secondary Lymphoid Tissue

33
Q

Cells and tissues of the immune system chart

A
34
Q

Monocytes/Macrophages:

A

Monocytes circulate in the blood & differentiate into macrophages upon migration into tissue (long-lived)
Macrophages are phagocytic, and are the mature form of a monocyte
Macrophages often produce soluble messengers that help orchestrate a wide range of adaptive and innate immune responses
Present antigens to T cells

35
Q

Dendritic cells:

A

Resident in the body’s tissues
During infection, recognizes infection and transports antigen to lymphoid organs
Present antigens to T-cells - important in T cell activation during adaptive immune responses

36
Q

Granulocytes: 3 types are=

A

Neutrophils, eosinophils and basophils

37
Q

Neutrophils

A

Phagocytic and enter sites of infection (short-lived)
Die in infected tissues  form pus (purulent inflammation)
Most numerous cellular component of innate immune system

38
Q

Eosinophils

A

Defense against parasites
Involved in hypersensitivity responses

39
Q

Basophils

A

Along with mast cells, protect mucosal body surfaces & release histamine in hypersensitivity responses
Also implicated in defense against parasites

40
Q

Mast cells

A

Reside in all connective tissues – only resident granulocyte and have a unique role
Orchestrate hypersensitivity responses (e.g. seasonal allergies), important in mucosal immune responses

41
Q

3 types of lymphoid progenitor cells

A

B cells, T cells, NK cells

42
Q

B cells

A

Bone marrow derived
Upon activation, differentiate into Ab-secreting plasma cells

43
Q

T cells

A

Thymus-derived (though originate in bone marrow)
Become either helper T cells (Th) or cytotoxic T lymphocytes (CTL)
Helper T (Th) Cells: Activate other cells (macrophages, B cells)
Cytotoxic T Cells (CTLs): Kill cells that express foreign molecules

44
Q

Do T and B lymphocytes look alike? Do they have receptors for specific or different antigens?

A

Yes, specific

45
Q

NK cells

A

(natural killer) Important in the innate immune system
Lack antigen-specific receptors
Kill infected & altered cells (e.g. malignant cells)

46
Q

Are lymphocytes the only adaptive immune cells?

A

No
Dendritic cells and macrophages are absolutely key in presenting antigens to T-lymphocytes
Many “innate” immune cells produce cytokines that inform helper T-cells about how to “help” other immune cells
Certain subsets of helper T-cells are dedicated to ONLY aiding innate immune responses
Mast cells, neutrophils, eosinophils, and macrophages are important at helping to clear antigens that are bound by antibody

47
Q

Lymphoid tissues. What are they? What are the 2 types?

A

Organized tissues where lymphocytes interact with non-lymphoid cells

Important in initiation/maturation of adaptive immune responses

2 types of lymphoid tissues
Primary (central) lymphoid organs
Secondary (peripheral) lymphoid organs

48
Q

Primary lymphoid organs

A

Where lymphocytes are generated and mature
Includes bone marrow & thymus
Both B and T cells are generated in the bone marrow
B cells mature in the bone marrow
Although additional maturation steps can occur in the spleen, it is not viewed as a primary lymphoid organ
T cells mature in the thymus

Once lymphocytes mature they leave primary lymphoid organs and are capable of responding to an antigen

49
Q

Secondary lymphoid organs

A

Where adaptive immune responses are initiated—antigens and B/T Cell receptors encounter each other
Exist to bring antigen and lymphocytes together
Lymph nodes, spleen, and MALT (mucosa-associated lymphoid tissue)

50
Q

Lymph nodes

A

Lie at junctions of lymphatic vessels
Collect extracellular fluid (lymph) and return it to the blood (via lymphatics)
Afferent lymphatics drain lymph and antigens from tissues, carrying it to the nodes where antigen is trapped

51
Q

Spleen: What does it do? What is it divided into?

A

Fist-sized organ located deep and lateral to the stomach
“Filter for blood”—collects blood-borne antigens & also destroys aged RBCs
B-cells in the spleen produce large quantities of antibodies and secrete them into the bloodstream
Most B-cells undergo some degree of maturation in the spleen
Organ is divided into red pulp & white pulp

Both pathogens and lymphocytes enter and leave the spleen in the blood

52
Q

What is the difference in red pulp and white pulp of the spleen?

A

Red pulp: Where old RBCs are destroyed

White pulp: Where lymphocytes surround arterioles entering organ

Further subdivided into corona and periarteriolar lymphoid sheath (PALS)

53
Q

Mucosa-associated lymphoid tissue (MALT):

A

Includes gut- and bronchial- associated lymphoid tissues (GALT, BALT, etc…)
Purpose is to collect Ag from mucosal surfaces
Specialized lymphoid tissue at the body’s “wet” surfaces required due to large surface area, rich with potential pathogens

54
Q

GALT

A

Includes tonsils, adenoids, appendix and Peyer’s Patches (PP)
PPs collect Ag from epithelial surfaces of GI tract via M cells
PPs composed of distinct T and B cell areas

55
Q

Immunogen vs hapten

A

Immunogen elicits immune response, hapten does not without being attached to a larger protein.

56
Q

True or False. Neutrophils, eosinophils and basophils appear to have more than 1 nucleus, where as mast cells have 1 clear mucleus.

A

True.

57
Q
A

Semester 2 Immunology (8 decks)

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