Module 1: Immunology Flashcards
Define: Immunology
Study of Chemical and Cellular defense against foreign substances
Define: Immunity
Body’s resistance to disease-causing microorganisms and damage by foreign substances
Innate Host Response is also called?
Natural/Native Immunity
What is Innate Host Response (Natural/Native Immunity)?
Non-specific, general recognition and response to “foreign” substance.
What kind of Barriers are used in Innate Host Response (Natural/Native Immunity)?
Physical and Chemical Barriers (e.g. Skin and mucous; certain proteins in blood and specific tissue cells; inflammation, phagocytosis)
What determines the nature of the Innate Host Response (Natural/Native Immunity)?
Route of transmission or portal of entry and type of microbe
What other names can Adaptive Immunity Response have?
Acquired Immunity Response or Induced Immunity Response
What is Adaptive (Acquired/Induced) Immunity Response?
- Specific response to “foreign” substance (usually microbe)
- Pre-committed cells and tissues respond against the “foreign” substance
- Chemical actions from certain cells
- Antibodies specifically against the microbe
What is Immune Response?
A sequence of related host defense events beginning when a host encounters a substance as being “foreign” or “non-self” and leading to cellular and chemical defensive action
Define: Antigen (Ag)
A foreign substance, such as microorganism, which triggers the immune response.
Define: Antibody (Ab) [Immunoglobulin (Ig)]
Antigen-specific proteins which bind to the antigen and assist in inactivating the antigen
Define: Phagocytes
Certain White Blood cells that ingest and digest (kill) invading microbes
What role do the Lymph nodes and Spleen play in immunity?
Site of some immune response activities
What cells originate in the Bone Marrow?
Stem Cells
What cells will the stem cell mature into?
- Erythrocyte (Red Blood Cell)
- Neutrophils
- Eosinophil
- Basophil
- Monocyte
- Lymphocytes
White blood cells are also called?
Leukocytes
Which Leukocytes are classified as Granulocytes?
Neutrophils
Eosinophil
Basophil
What are the characteristics of a Neutrophil?
- Primary phagocytic Cell
- Mature at rate of 10^10
- Circulate about 6.5 hrs. Then adhere to endothelium of blood vessels and wait to respond to inflammation
Which Leukocyte is numerous in allergic responses.
Eosinophils
Which Leukocyte (White Blood Cell) is involved in the inflammatory process?
Basophils
This Leukocyte is moderately phagocytic. Matures into Macrophages and dendritic cells. Responds to inflammation signals.
Monocyte
The primary Phagocyte Cells are?
Macrophages and Neutrophils
A Macrophage is how many times larger than a monocyte when mature?
10 times
What are some key characteristics of Macrophages?
- Large phagocytic cells (mature from monocyte)
- Major Phagocytic cells, not as numerous as neutrophils
- Possess many broad-specificity receptors enabling it to capture a wide range of pathogens
- Major line of defense (Phagocytosis and antigen presentation) against invading microbes and abnormal or defective host cells
- Can serve as Antigen-Presenting Cells (APC)
Define: Innate Host Response (Natural/Native Immunity)
Nonspecific, general response to “foreign” substances, including INFLAMMATORY RESPONSE. (Not directly part of the immune system)
What types of response occurs with Innate Host Response?
Physical and Chemical Barriers
How is defense accomplished with physical and chemical barriers in Innate Host Response?
- Skin and Mucous
- Certain proteins in blood and from specific tissue cells
- Phagocytosis
What determines the nature of the response?
Route of transmission or portal of entry and type of microbe.
Characteristics of Inflammatory Response?
Chemicals in serum and tissues respond to antigen presence- kinins, fibrinopeptides, clotting factors, lysozyme, histamine, cytokines, etc..
What occurs in a chemical response?
- Vasodilation and increased permeability of capillaries (blood vessels become “leaky”
- “Call” phagocytic white blood cells to move to the site of invasion and assist in killing (removing) the invading microbe.
- Phagocytosis occurs, often producing pus (debris of phagocytes and bacteria) and swelling
What is phagocytosis?
Antigenic substance is engulfed and digested by certain white blood cells. (Phagocyte will have a sticky surface)
What are the primary cells involved in Phagocytosis?
Macrophage and Neutrophil
What is Chemotaxis?
- Movement of phagocyte toward the site of inflammation/intrusion.
- “Called by cellular products or complement components (C5a)
What is adherence (phagocytosis process)?
Phagocyte adheres to antigen/intruder
May be hindered by bacterial capsule or surface protein
Describe Ingestion during phagocytosis?
- Pseudopod of phagocyte surrounds the foreign material
- Phagocyte encloses the foreign material into a phagosome
How is digestion accomplished in phagocytosis?
- Lysosomes (cytoplasmic granules) containing powerful digestive enzymes and bactericidal substances
- Lysosomes combine with phagosomes forming phagolysosomes in which the foreign material is digested (killed)
- Waste is discharged.
What is an Antigen (Ag)?
Specific “foreign” substance which STIMULATES an IMMUNE RESPONSE (immunogenic) when introduced into the body and REACTS with ANTIBODIES or T-CELL RECEPTORS
Characteristics of Antigens (Ag)?
- Substance appears foreign to host’s immune system (May be human host’s body constituents (self) that are damaged or malfunctioning (autoimmunity)
- Relatively large molecule (Molecular weight 10,000+)
- Chemical nature- protein with complex 3-D Configuration
What factors contribute to the ability or quality of a molecule to be a good immunogen (ie. Quality and degree of host response)
Route, quantity, timing, and ability to be degraded
What is the name of the Antigenic Determinant site/portion of the antigen?
Epitope
Define: Epitope
Specific part of the immunogen that specifies or determines the exact antibody to be produced.
The epitope is the portion of the antigen that will combine with what?
Specific antibody or T-cell receptor
Different epitopes (even on same Ag) will induce….
production of slightly different antibodies (Ab)
What is the quality of the epitope based on?
- Exposure to the immune system
- 3-dimensional shape of the molecule
What is an Immunoglobulin (Ig) [Antibody (Ab)]?
Antigen specific proteins which bind to specific sites on antigens and assist in inactivating the Ag by attaching to it.
Give the general characteristics of Immunoglobulins.
- Antigen-specific glycoproteins (4-18% carbohydrate) produce/secreted by plasma cell (Sole function of plasma cells)
- Categorized into Classes; Ig A, Ig, D, Ig E, Ig G, Ig M
Describe the Basic Characteristics of Immunoglobulins (Ig) structure.
- “Y” shaped with ends designated as Fab and Fc
- Fab (Fragment Antigen Binding) sites- antigen specific binding sites (2 Fab sites per monomeric molecule)
A Fab is considered to be the ________ specificity for specific antigen.
“Lock and Key”
Fc (Fragmented Complement-binding) region?
Binds to phagocyte (tail region of Ab that interacts with cell surface receptors called Fc receptors and some proteins of the complement system)
What type of molecule is an immunoglobulin and it consist of?
Macromolecule with at least one monomer (one basic unit) comprised of two heavy chains and two light chains. Some classes are comprised of more than one monomer
Describe the Heavy Chains of an immunoglobulin.
- At least one pair, 50-70 kD m.W- identical to each other within macromolecule
- Long chain of amino acids- 4-5 domains (110 amino acids each)
- Constant region (CH
- Variable region (VH)
Characteristics of Constant Region (CH) of heavy chain of immunoglobulin.
- Consists of 3 or 4 domains (CH1, CH2, CH3, CH4)
- Determines class of immunoglobulin 5 amino acid sequences. igM, IgG, IgA, IgD, IgE
- IgM and IgG have complement binding sites.
Characteristics of Variable region (VH) of heavy chain of immunoglobulin.
-Amino acid sequence and 3-d structure accounts for ability to recognize and bind with a particular epitope
Describe the light chains of immunoglobulin.
- One pair; 23 kD m.w.
- Short chain of amino acids
- Constant region (CL)
- Variable region (VL)
Characteristics of Constant region (CL) of light chain of immunoglobulin.
-Two types (2 sequences)- Kappa and Lambda types (4 subtypes)
Characteristics of Variable region (VL) of light chain of immunoglobulin.
Amino acid sequences vary from one immunoglobulin to another; match with variable region of corresponding heavy chain.
What bond holds the chains together of an immunoglobulin?
Disulfide bonds
The flexible “hinge” region on the pair of heavy chains allow for what?
- Bend into a y or T Shape
- Shape changes necessary for binding with antigen and exposure of complement binding site
Immunoglobulin molecule forms with how many antigen binding sites?
Two antigen binding sites
The antigen binding sites are named what?
Fragment antigen binding
How are the Fab sites formed?
Complementary shape of the variable regions of one heavy and variable region of one light chain
What is the Fc Region of an immunoglobulin structure?
Fragment Complement-binding- site for complement activation and attachment to white blood cells
What region of an immunoglobulin will bind to an epitope?
Variable region of the Fab
What is lymphoid tissue?
Tissues where antigens interact with cells of the immune system
What tissues are lymphoid tissues?
Lymph Nodes and Spleen
What role do Lymph Nodes and Spleen play?
Pieces of the antigen are processed (filtered) through lymph nodes and/or spleen in a filtering manner where antigens come in contact with cells of the immune system. Those cells become activated to go into action (pre-determined type of action)
How are Lymph Nodes utilized in the immune system?
Lymphatic fluid containing antigens and Antigen Presenting Cells flow through lymph nodes where the antigens encounter and activate pre-committed lymphocytes.
Lymph nodes respond to what type of infections?
Local or Regional Infections
How is the spleen utilized in the immune system?
Filters blood and traps blood-borne antigens/
The Spleen responds to what type of infections?
Systemic Infections
Where in the Lymph Node is the Ab production area?
Medula
Where in the Lymph Node are T-lymphocytes and APC’s found?
Paracortex
Within the Primary Follicle of the Lymph Node what lymphocyte is found?
B-Lymphocytes
Within the white pulp of the Spleen Lobule what Lymphocyte is found?
T-Lymphocyte
B-Lymphocytes are found within what area of the Spleen Lobule?
Follicle
Name other Non-Thymic Lymphoid Tissue.
- Mucosal-Associated Lymphoid Tissue (MALT)
- Gut-Associated Lymphoid Tissue (GALT)
- Tonsils
- Bronchus-Associated Lymphoid Tissue (BALT)
Gut-Associated Lymphoid Tissue (GALT) is found?
Appendix and Peyer’s Patches- Lymphoid nodules on outer wall of intestines
What is a Major Histocompatibility Complex (MHC) proteins?
Proteins on the surface of tissue and blood cells which identify cells belonging to a specific individual.
Recognition of Self vs Non-self is determined by?
Presence or absence of specific proteins on the human cell surface
Describe a MHC Class I.
- One amino acid chain
- Found on virtually every cell in the body
Describe a MHC Class II.
- Two Amino Acid Chains
- Found only on immunocompetent cells, particularly B-cells and macrophages
Name the types of Lymphocytes?
T-Lymphocytes (T-cell)
B-Lymphocytes (B-cell)
Natural Killer (NK) Cells
How are lymphocytes identified and differentiated?
Clusters of Differentiation (CD#)
What are the characteristics of CDs (Clusters of Differentiation)?
- Protein complexes on the surface of lymphocytes
- Serve as receptors or attachment sites
- Identify different stages of lymphocyte development
What are the steps taken during Phagocytosis?
- Chemotaxis
- Adherence
- Ingestion
- Digestion
These are specific to an antigen and to which a cell is “pre-committed” and they develop as attachment sites for specific types of foreign antigen molecules.
Antigen-Specific Surface Receptors (T-cell Receptors [TCR] and B-cell Receptors [BCR])
What is Immune Tolerance?
Mature lymphocytes will be tolerant of antigens on our own “self” MHC molecules. No immune response against them.
Where do T-lymphocytes (T-cells) mature and then concentrate?
Thymus and concentrate in Lymph nodes
The thymus decreases and stops producing T-cells as we age. What does this mean about T-cells?
T-cells are self replicating
Name the T-cell Surface markers.
- CD3- identifies mature T-cell
- CD28- receives activation co-signal from CD80/86 molecule on APC
- CD40-receptor(CD40-R) (CD4 cell, TH cell)- binds with CD-40 molecule on B-cell
- LFA-1 (Leukocyte Function-associated Antigen-1)- Adhesion molecule on T-cells
T-cell Receptors (TCR) are
Antigen Specific
Subpopulations (CD receptors) develop with specific functions, and are identified by CD’s present. Name some.
CD4- Helper (TH1, TH2)
CD8- Cytotoxic
CTL (Cytotoxic T-lymphocyte)
Where do B-lymphocytes (B-cells) mature and then concentrate?
Bone Marrow
Concentrate- peripheral lymphoid tissues (Spleen, MALT, Lymph nodes, and bone marrow)
What CD surface markers are found on B-cells?
CD40- binding with certain T-lymphocytes
CD19, CD20, CD21- Used for Identification
CD80/86- Produced when B-cell acts as APC and does not initially have. (Used to bind to T-cells)
B-cell Receptors (BCR) are
Antigen Specific (cell may carry 100,000 molecules)
When activated B-cells differentiate into?
Plasma Cells- manufacture immunoglobulins
Plasma Cells Manufacture what?
Immunoglobulins (Ig)
B-cells can act as what when they bind to an Ag and present it to T-cells?
Antigen-Presenting Cells (APC)
What significant surface molecules do Antigen-Presenting Cells (APC) have?
- MHC-II- Carries a piece of digested Ag for Ag recognition
- CD80/86 (B7-1 and B7-2)- Co-Activation molecules
- ICAM-1 (Intercellular Adhesion Molecule-1)- principal binding receptor for LFA-1 (Leukocyte Function-associated Antigen-1)
- LFA-3- binding molecule for CD2
