Introduction to the Immune System Flashcards Preview

HDM Exam 1 and 2 > Introduction to the Immune System > Flashcards

Flashcards in Introduction to the Immune System Deck (57)
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1
Q

Define the roles of the Immune System

A
  1. Defense against infection
  2. Defense against tumors
  3. Injure cells and induce pathologic inflammation
  4. Recognizes and responds to tissue grafts and newly introduced proteins
2
Q

Define Adaptive Immunity

A

Response of Ag-specific lymphocytes to Ag includes MEMORY

3
Q

Define Innate Immunity

A

Protection against Ag that relies on mechanisms that exist before exposure

4
Q

What is CD?

A

Cluster of Differentiation

Cell surface molecules expressed on various cell types are designated by a CD number

5
Q

CDs to memorize

A
CD21 = CR2 = C3dR
CD25 = IL-2Ra
CD152 = CTLA4
CD95 = Fas
6
Q

Define Cytokines

A

Molecules that tell other cells what to do, mediate the immune response
They act through autocrine, paracrine, and exocrine actions.
Pleiotropic and redundant
They include: IL, TNF, IFN-a/B/y, TGF-B, CSF

7
Q

Define Chemokines

A
They tell other cells to come here. 
Chemotatic cytokine (IL-8)
8
Q

Define Immunogen

A

Ag that evokes a specific immune response

9
Q

Define Tolerogen

A

Ag that induces immunologic tolerance

10
Q

Define Endogenous Ags

A

Body’s own cellular components or intracellular pathogens

11
Q

What are the different classifications of endogenous Age?

A

Autoantigens: SELF-Ag

Alloantigens: Tissue specific Ag, which is present in one individual but not another

Intracellular pathogens: Viruses, parasites, intracellular bacteria

12
Q

Define Exogenous Ags

A

Ags that enter body or system, freely circulate in body fluids and are trapped by APCs

Uptake of Exo Ags by APCs mediated by phagocytosis

13
Q

What structures make up Innate Immunity?

A

Epithelial Barriers, Mast Cells, Phagocytes, Dendritic Cells, Complement, NK cells and ILCs

14
Q

What structures make up Adaptive Immunity?

A

B-lymphocytes (which may become Plasma cells)

T-lymphocytes (T-helpers, Cytotoxic T, Tregs, NK cells)

15
Q

What are the Characteristics of Innate Immunity?

A
Respond rapidly 
Normally inactive in absence of infection 
Found in ANY vascular tissue 
Limited diversity 
NO Memory 
Stimulates Adaptive Immunity
16
Q

What cell types are Phagocytes?

A

Neutrophils
Monocytes/Macrophages
Dendritic Cells

17
Q

What are some characteristics of Neutrophils?

A
AKA: polymononuclear 
Circulate, short-lived
First at Site of Infection 
Make up 54-62% of WBCs
Component of pus (pyogenic)
18
Q

CD marker for Neutrophil

A

CD15, CD16b

19
Q

_1__ is present in the bloodstream and turns into _2__ in tissues. What phagocytes fill in the blanks?

A
  1. Monocytes

2. Macrophages

20
Q

What are some characteristics of Monocytes/Macrophages (MO)?

A

Respond to site of inflammation in 1-2 days
Survive longer than neutrophils
Levels increased in chronic inflammation, immune-mediated diseases, stress, and necrosis

2 Major functions by:
M1 classical MO
M2 alternative MO

21
Q

Define M1 classical macrophages.

A

They are induced by innate immunity to play a role in INFLAMMATION.

22
Q

Define M2 alternative macrophages.

A

They are induced by IL-4 and IL-13 to play a role in TISSUE REPAIR and CONTROL of INFLAMMATION.

23
Q

Other functions of MOs at various stages include?

A
Garbage collectors ("resting" state)
Ag presenting cells ("activated" state) 
Vicious killers ("Hyperactivated" state)
24
Q

CD marker for MOs

A

CD14 (TLR4)

Recognizes and binds to LPS

25
Q

What are some characteristics of Dendritic Cells?

Include surface expression and CD marker

A

Professional APCs
Capture Ag, migrate to lymphoid tissue and present Ag to mature, naive T cells

Express: High levels of Class II HLA/MHC and CD80 (B7)

*May also present Ag with Class I HLA/MHC

26
Q

What is significant about dendritic cells expressing high levels of Class II HLA/MHC + CD80?

A

It makes Dendritic cells better APCs than Macrophages and B-cells.

27
Q

What is the major function of APCs?

A

They are the bridge b/w innate and adaptive immunity.

28
Q

Define Specific Immunity.

A

Distinguish b/w different, closely related, microbes and molecules

29
Q

Define Acquired Immunity.

A

Potent protective responses are “acquired” by experience

30
Q

Characteristics of Adaptive Immunity

A

Specific for Ag
Diverse - receptors are produced by somatic recombination of gene segments
Has Memory

31
Q

What are some characteristics of Eosinophils?

A

Differentiate in response to IL-5
Responsible for combating multi-cellular parasites
Major role in atopic diseases

32
Q

What are some characteristics of Basophils?

A

Bi-lobed nucleus
Release pharmacologically active substances contained within granules
Role in Atopic diseases
Combat parasitic diseases

33
Q

What are some characteristics of Mast Cells?

A

2 types: tissue and mucosal

Can be stimulated to degranulate by direst injury, chemicals, alcohols, and certain Abs, cross linking of IgE receptors, or activated C’ proteins

Key role in inflammatory process
Atopic responses

34
Q

CD marker for Mast cells

A

CD23

35
Q

Mature, Naive vs. Effector vs. Memory lymphocytes

A

Naive is when It has not been activated by Ag yet.
Effectors have been activated by Ag
Memory lymphocytes remember that you have immunity to a pathogen.

36
Q

Humoral vs. Cell-mediated Immunity

A

Humoral - Antibodies neutralize and eradicate exogenous Ags (B-cells, produce immunoglobulins)

Cell-mediated - Activation of cell to eradicated endogenous antigens (T-cells)

37
Q

Function of Effector B-cells

CD marker?

A

Neutralization of microbe
Phagocytosis
Complement activation

CD19, CD21

38
Q

Function of Helper T-cells

CD marker?

A

Activation of macrophages
Inflammation
Activation (proliferation and differentiation) of T and B lymphocytes

CD3, CD4

Th1: IL-2, IFN-y
Th2: IL-4, IL-5, IL-13
Th17: IL-17, IL-22

39
Q

Function of Cytotoxic T-cells

CD marker?

A

Killing of infected cells

CD3, CD8

40
Q

Function of Regulatory T-cells

CD marker?

A

Suppression of Immune Response

CD3, CD4, CD25, IL-10, TGF-B

41
Q

How does the Lymphatic system work?

A

It drains the tissues and transports lymphocytes and antigens to secondary lymphoid tissue, where the lymphocytes can interact with the antigens.

As blood is circulating, some fluid leaks out of the capillaries. This fluid is lymph. Most of the fluid will return back to the circulatory system through one way valves into the lymphatic vessels.

Lymph moves via muscle movement.

42
Q

What occurs in the lymphoid tissue?

A

Dendrites or APCs will enter the lymphoid tissue through the Afferent lymphatic vessels. Lymphocytes will enter through the high endothelial venues. They follow lymphocyte specific chemokine to different regions of tissue (different zones for B and T cells). There they are activated by an APC and leave through the circulatory system.

If they are not activated they leave through the Efferent lymphatic vessels and go to the next lymphoid tissue. They will eventually end up at the thoracic duct and go back into circulation.

43
Q

Function of Natural Killer Cells in Innate Immunity

CD marker?

A

Recognize infected, stressed, or malignant cells and kill them by releasing granzymes and perforins leading to apoptosis of target cell

Activated by IL-12, IL-15, and Type 1 IFNs

Activated NKs secrete IFN-y (activates macrophages)

CD16, CD56

44
Q

What is the difference b/w NK cells and Cytotoxic T cells?

A

NK cell don’t recognize specific antigens like cytotoxic T cells do.

45
Q

What is the relationship b/w NK cell and macrophages?

A

NK cells are activated by IL-12, which are release by macrophages. NK cells will then release IFN-y, which hyperactivates macrophages. Macrophages will then produce more IL-12, activating more NKs… and so on.

46
Q

What is a primary immune response?

A

It is the first time an Ag is encountered.
Activation of naive cells to perform effector functions
Generation of memory cells

47
Q

What is a secondary immune response?

A

It is the second time an Ag is encountered.
Memory cells are activated
There is a stronger, faster effector response

48
Q

Describe the Mucosal Immune System.

A

Largest SA as barrier against outside world
More bacterial DNA than human
Microbiome - part of innate immune system
Contains very specialized cells and responses for protection
IgA - Ab abundantly produced in mucosal tissue, bind/neutralizes microbes

49
Q

Define the Cutaneous Immune System.

A

SKIN - second largest barrier
Has specialized innate and adaptive cells and responses
Langerhans - primary APC in epidermis

50
Q

Phases of Adaptive Immune Response

A

Antigen Recognition (T cells activated by APCs, B cells by Antigens)

Lymphocyte Activation (Clonal expansion and differentiation of lymphocytes - Ab producing cells and effector cells)

Antigen Elimination (by Abs and effector Ts)

Homeostasis (Apoptosis of infected cells)

Memory (surviving memory cells)

51
Q

Describe Systemic Immunity.

A

Lymphocytes travel to secondary (peripheral) lymphoid organ where they will come into contact with antigens that traveled from site of infection via lymph.

Antigens also travel to the spleen via blood. Activation of lymphocytes and initiation of adaptive immune responses. Effector Ts and Abs migrate to site of infection.

52
Q

Define Active Immunity.

A

Introduction of an Ag that provokes an adaptive immune response. Has memory!

Artificial = vaccine 
Natural = infection
53
Q

Define Passive Immunity.

A

Introduction of Ab or antiserum into naive recipient
No memory!

Artificial = IVIG (intravenous immunoglobulin) 
Natural = maternal
54
Q

What are the Primary lymphoid organs? Secondary?

A
Primary = Bone marrow and Thymus 
Secondary = Spleen, Lymph node, mucosal immune tissue
55
Q

Describe the time line for Innate and Adaptive Immunity.

A

Phase 1 (0-4 hrs) = Non-induced Innate - skin, pH, saliva

Phase 2 (4-96 hrs) = Induced Innate, broadly specific - phagocytosis, C’ system, inflammation, cytokines

Phase 3 (>96 hrs) = Induced Adaptive, highly specific - B cells (Ab), helper Ts, CytT

56
Q

Circulatory immune cells vs. Tissue immune cells

A

Circulatory = Neutrophils, Eosinophils, Basophils, Monocytes, T/B/NK cells, platelets, RBCs

Tissue = Tissue eosinophil, Mast cell, Macrophage, T-lymphocyte, Plasma cell, NK cell

57
Q

Describe the migration of T and B lymphocytes in secondary lymphoid tissue.

A

Naive T-cells enter through high endothelial venules
Adhesion molecules used by Ts to bind to endothelium constitutively expressed
Chemokines produced in T-cell zones bind to chemokine receptor CCR7 on naive T-cells
Chemokine interaction with CCR7 causes T-cells to bind tightly to HEVs
Naive Ts migrate to T-cell zone

Naive B = similar
Migrate to LN follicles being guided by chemokines that bind to CXCR5 receptor on B cells