Immunology Flashcards
The cells and molecules responsible for immunity, and their collective and coordinated response to the presence of foreign substances.
Immune System
The overall actions of the immune system to provide immunity through a sequence of integrated host defense events when a host encounters a “foreign” substance and leading to cellular and chemical defensive actions.
Immune Response
The body’s resistance to disease-causing microorganisms and damage by foreign substances.
Immunity
Natural/native immunity. Non-specific, general recognition & response to “foreign” substances, including inflammatory response.
Innate Host Response
The route of transmission & microbe type determine nature of response.
Innate Host Response
This is the acquired/induced response
Adaptive immunity
Adaptive Response is _____ to “foreign” substances.
Specific
Pre-committed lymphocytes in the lymph nodes and spleen respond against the “foreign” substance
Adaptive immunity
A foreign substance, such as a microorganism, foreign blood cell, cells of transplanted organs, or toxins.
Antigen (Ag)
What triggers an immune response when introduced into the body?
Antigen (Ag)
What is the basic molecule of an antibody?
Y shaped
Antibody portion that is antigen-specific, and binds to a specific site on antigen molecules and assists in inactivating the antigen by attaching to it.
Fragment Antigen-Binding (Fab)
Part of the antibody that can bind to a phagocytic cell.
Fc portion
What is categorized into classes: Ig A, Ig D, Ig E, Ig G, Ig M?
Antibody (Ab) [immunoglobulin Ig]
Antigen specific proteins
Antibody (Ab) [immunoglobulin Ig]
What do phagocytes do?
ingest and digest invading microbes
- Ingestion
- Digestion
- Waste
Phagocytes are certain _____ blood cells
white
Specialized cells located in various tissues that help initiate the immune response by recognizing, “processing”, and presenting Ag to other cells of the immune system
Dendritic cell
Where do stem cells originate?
Bone marrow
About how many erythrocytes are there per mcL?
4-6 million
About how many leukocytes are there per mcL?
4,500-11,000
Which white blood cells are involved in the inflammatory process?
Basophiles (0.5-1%)
Which white blood cells increase in allergic responses?
Eosinophils (1-5%)
What are the primary phagocytic cells that ingest/kill foreign material?
Neutrophils (45-75%)
About how many hours do neutrophils circulate for?
6-10 hours
What do neutrophils do after they circulate in the blood?
adhere to the endothelium of the blood vessels and wait to respond to inflammation; short lived.
What matures into macrophages & dendritic cells and responds to inflammation signals?
Monocyte (2-8%)
What are precommitted during maturation to respond to specific antigens?
Lymphocytes (25-40%)
What are the types of lymphocytes?
T-cell, B-cell, and Natural Killer Cell
Approximately, how many lymphocytes are produced per day?
10^9
The average lymphocyte completes a cycles of circulation through the blood and lymphatic system in about how many days?
1 to 2 days
What percentage of total body lymphocytes are present in the circulating blood?
About 1%
Where are the lymphocytes that are not circulating in the blood (the other 1 %)?
adhered to the inside of blood and lymphatic vessels until needed during infection.
What are the large phagocytic cells that mature from monocytes?
Macrophages
These are about 10 times the size of monocytes
Macrophages
These are a major phagocytic cell but not as numerous as neutrophils
Macrophages
Possess many broad-specificity receptors enabling it to capture a wide range of pathogens and can serve as Antigen-Presenting Cells (APC).
Macrophages
What is a major line of defense against invading microbes and abnormal or defective host cells?
Macrophages
Tissues where antigens interact with cells of the immune system
Lymphoid Tissues
Where are pieces of the antigen processed through in a “percolating/meandering” manner?
lymph nodes or spleen
A site containing lymphatic fluid that responds to local or regional infection?
Lymph Nodes
Blood-borne antigens and Antigen-Presenting Cells meander through which organ where they encounter and activate precommitted lymphocytes?
Spleen
Site that responds to systemic infections?
Spleen
MALT
Mucosal-Associated Lymphoid Tissue
GALT
Gut-Associated Lymphoid Tissue
Appendix and Peyer’s patches, lymphoid nodules on outer wall of intestines
GALT
Bronchus-Associated Lymphoid Tissue
BALT
What are some other Non-thymic Lymphoid Tissue?
MALT, GALT, BALT, Tonsils
What stimulates an immune response and reacts/binds with antibodies or T-cell receptors?
Antigen (Ag)
What are the characteristics of an antigen?
- Substance appears foreign to the host’s immune system
- Size- relatively large molecule
- Chemical nature- usually protein with complex 3-D configuration
- Antigenic determinant
What is the usual molecular weight of an antigen?
more than 10,000
What are some factors that affect the ability or quality of a molecule to be a good immunogen?
Route, quantity, timing, and ability to degrade
The specific part of the immunogen that specifies or determines the exact antibody to be produced
Epitope
The epitope is the portion of the antigen that combines with?
A specific antibody or T-call receptor
What will induce the production of slightly different antibodies?
Different epitopes (even on the same antigen)
The quality of the epitope is based on what?
The exposure to the immune system and the 3-dimenstional shape of the molecule.
What are the Major Histocompatibility Complex proteins (MHC)?
proteins on the surface of tissue and blood cells which identify cells belonging to a specific individual.
The recognition of self vs. non self is determined by?
the presence or absence of specific proteins on the human cell surfaces.
Where are class one (one amino acid chain) MHCs found?
on virtually every cell in the body
Where are class two (two amino acid chains) MHCs found?
found only on certain cells of the immune system, particularly dendritic cells, macrophages, and B-cells.
When do T-cells recognize antigens?
when they are presented by MHC molecules
Blood and tissue of another person is sensed as being?(except for identical twins)
Non-self
Specialized cells located primarily in tissues where they are exposed to the external environment (ex. lymphoid tissue; epithelia of skin, gastrointestinal, respiratory tracts, and certain other tissues) that participate in initiating antigen recognition and immune response
Dendritic cells
Langerhans Cells (Dendritic Cells)
Skin
Intestine (Dendritic Cells)
various types of DC
Alveolar macrophage (Dendritic Cells)
lung
Kupffer cells (Dendritic Cells)
Liver
Microglial cells (Dendritic Cells)
Brain
Interdigitating Dendritic Cells
Lymph nodes and spleen
What is the primary role of the dendritic cells?
VERY significant role in initiating antigen-specific T-call responses by capturing and presenting antigens
The spidery shape (tentacles) of dendrites helps with?
Capturing foreign antigens. They possess a large surface area which facilitates capturing foreign antigens
After dendrites process foreign antigens what do they do with the peptides?
Place peptides onto MHC 2 molecules on cell surface of the immune system
Where do the dendrites migrate through to present antigens to cells of the immune system?
blood and lymph to spleen and lymph nodes
What are the physical and chemical barriers to the innate host response?
- Skin & Mucous
- Certain proteins in blood from specific tissue cells
- Phagocytosis
What determines the nature of response in a innate host response?
Route of transmission, or portal of entry and type of microbe
____ in serum & tissue responds to antigen presence -kinins, fibrinopeptides, clotting factors, lysozyme, histamine, cytokines etc.
Chemicals
What are the steps of the inflammatory response in the innate host response (pg 9 of study guide)?
- vasodilation and increased permeability of capillaries; blood vessels become “leaky”
- “Call” phagocyte white blood cells to move to the site of invasion and assist in killing the invading microbe
- Phagocytosis occurs, often producing pus (debris of phagocytes and bacteria) & swelling.
What is phagocytosis?
antigenic substance is engulfed and digested by certain white blood cells.
What are the primary cells involved in phagocytosis?
Macrophage and neutrophil
Movement of phagocyte toward the site of inflammation/intrusion; “called” by cellular products or complement components (C5a)
Chemotaxis
What are the steps of phagocytosis?
- Adherence
- Ingestion
- Digestion
- Phagocyte adheres to antigen/intruder
2. Hindered by bacterial capsule or surface protein
Adherence
- Pseudopod of phagocyte surrounds the foreign material
2. Phagocyte encloses the foreign material into a phagosome
Ingestion
- Lysosomes (cytoplasmic granules) contain powerful digestive enzymes and bactericidal substances
- Lysosomes combine with phagosomes forming phagolysosomes in which the foreign material is digested.
- Waste/ debris is discharged.
Digestion
True or False: Lymphocytes are long-lived and “self-replicating”
True
How are lymphocytes identified and differentiated?
Clusters of Differentiation ( CD#)
What are characteristics of clusters of differentiation (CS)?
- CDs are protein complexes on the surface of lymphocytes
- CDs serve as receptors or attachment sites
- CDs identify different stages of lymphocyte development and different functions of the cell.
True of False: during maturation and before an encounter with an antigen, lymphocytes become precommitted or programmed to respond to an encounter with a specific antigen.
True
The process by which individual T&B lymphocytes are engaged by antigen and cloned to create a population of antigen-reactive cells with identical antigen specificity,
Clonal Selection
T-cell receptors (TCR), B-cell receptors (BCR) are specific to the antigen to which this cell is precommitted and they develop as attachment sites for specific types of foreign antigen molecules.
Antigen-Specific Surface Receptors
All lymphocytes in the same clone have the same ______ specificity
antigen
Immature lymphocytes undergo a large number of variable gene recombination’s for surface receptor molecules resulting in what?
Each lymphocyte having the capability to react with (respond to) a single type of antigen.
Antigen-specific lymphocyte reproduces copies of itself , thus forming?
Clone of millions of antigen-specific cells
The mature lymphocytes will be tolerant of antigens on our own “self” MHC molecules; and, therefore, will not mount an immune response against them. [Lymphocytes are not permitted to mature if they react to “self antignes”
Immune Tolerance
Where do T-lymphocytes mature?
Thymus, then concentrate in lymph nodes
What are the T-cell surface markers?
- CD3
- CD28
- CD40
- LFA-1 [Leukocyte Function-associated Antigen 1)
What does CD3 do?
Identifies mature T-call
What does CD28 do?
Receives activation co-signal from CD80/86 molecule on APC
What does CD40-receptor (on CD4 cell, Th cell) do?
Binds with CD-40 molecule on B-cell
What is LFA-1?
an adhesion molecule on T cells
True of False: T-cell receptors (TCR) are antigen specific?
True
Where do B-lymphocytes matures?
In the bone marrow
Where do B-lymphocytes concentrate?
peripheral lymphoid tissues- spleen, MALT, lymph nodes, and bone marrow
What are the surface markers of B-lymphocytes?
CD40
CD19, CD20, CD21
Produces CD80/86 when B-cell acts as APC
What are CD40 significant for?
Significant for binding with certain T-lymphocytes
CD19, CD20, CD21 are used for?
identification
True or False: B-cell Receptors (BCR) are antigen-specific
True
Can B-cells act as an Antigen-Presenting Cells (APC)?
Yes, by binding Ag to the specific receptors on B-cell surface and ‘presenting’ it to T-cells.
Upon activation, B-cells differentiate into?
plasma cells
The B-cells that differentiate into plasma cells manufacture?
immunoglobulins
What are the significant surface molecules APC possess?
MHC 2
CD80/86
ICAM-1
LFA-3
What do MHC 2 do?
carry (presents) a piece of the digested antigen- for antigen recognition.
What are CD80/86?
Co-Activation molecules
What is ICAM-1?
the principle binding (receptor) molecule for LFA-1
What is the binding molecule for CD2
LFA-3
Antigen-Presenting Cells (APC) binds antigen to specific receptors on the APC surface, then they do what?
place some of the digested antigen on the MHC-2 molecule and “present” it to the helper T cells
What 5 things do Antigen-Presenting cells do?
- Possess significant surface molecules
- Antigen-Presenting Cells (APC) binds antigen to specific receptors on the APC surface, then place some of the digested antigen on the MHC-2 molecule and “present” it to the helper T cells
- Produce Interleukin-1 (IL-1)
- Assisted by cytokines produced by lymphocytes
Produce IL-12
What does Interleukin-1 assist with?
Activation of lymphocytes
What does IL-12 do?
Enhances T-cell development
Example of dendritic cells as APC
capture antigenic material, then process and present Ag on MHC2
Example of Macrophage as APC
capture antigenic material via phagocytosis, then digest and present Ag on MHC2
Example of B-lymphocytes
capture “digested” antigenic material via antigen-specific B-cell receptors (B cells are not phagocytic) and present Ag on MHC2
Small proteins produced by specific human cells and which act as chemical mediators of the immune system to cause or enhance certain actions or functions of the immune system
Cytokine products of cells
IL-1
Macrophages, APCs
Co-stimulates TH cell activations, promotes T-cell proliferation (stimulates IL-2 receptors); inflammation
IL-2
CD4-cells
T&B cell growth factor; activates & enhances T, B, and NK cells.
IL-4
Activated CD4-cells
Co-stimulates B cells; Promotes B-cell growth & differentiation; Promotes IgE reactions
IL-5
Activated CD4 cells
Stimulates differentiation of B-cells & Eosinophils; Promotes IgA & IgE
IL-6
Macrophage, T-cells
Mediates acute-phase response; enhances B-growth; induces B-cell differentiation to plasma cell
IL-10
CD4 cells
Inhibits cytokine synthesis; down-regulates cellular response; enhances immunoglobin secretion
Tumor Necrosis Factor, TNFa,b
Macrophages & T-lymphocytes
Inflammation; activates macrophages, granulocytes cytotoxic cells; kills tumor cells; enhances phagocytosis
Colony Stimulating Factor (GM-CSF)
T-cells, & other
Stimulates production & function of granulocytes and macrophages
MIF
T-cells
Macrophages inhibition factor
MAF
T-cells
Macrophage activating factor
Interferon, IF a & b
Leukocytes
Antiviral activity, enhance MHC-1. activate NK
Interferon-y, IF-y
T-cells
Enhance & activate macrophages, CTL, and NK cells; promotes inflammation.
Type of immunity that remembers the antigen to which they responded and remain primed for future action
Adaptive Immunity Response
What are the two type of adaptive immunity responses that may interact with each other?
- Cell-Mediated Response
2. Humoral Response
Cell-Mediated Response
Defensive activities based on the action of pre-committed T-lymphocytes that move into action to kill the invader or activate other parts of the immune system through the production of chemicals which directly fight the antigen or chemicals that help regulate the immune response.
Defensive activities based on the role of antigen-specific immunoglobulins (Ig)
Humoral Response
What are the steps of the humoral response?
- Pre-committed B-lymphocytes are activated to transform into plasma cells which produce Ig
1. immunoglobulin bind to the respective antigen
2. Leads to phagocytosis or antigen destruction
3. Ig remains in circulating serum for month to years providing protection.
The humoral response assists immunoglobulins in removing antigens usually by
enhancing phagocytosis.
What are the major cells involved in the cell mediated immunity system?
Antigen-presenting cells
T-lymphocytes (Helper and Cytotoxic)
Natural Killer cells
What are the characteristics of the natural killer cells?
Possess CD16 and CD65 surface proteins, but not CD3
