Immunology Flashcards
What are the types of immunity?
-innate
-adaptive
Innate immunity
-general response to broad range of pathogens
-No memory after exposure
-rapid response after several hours
-everyone has it, eat bacteria, kill them, and tell adaptive immunity
What are the primary effector cells for innate immunity?
-Phagocytes, engulf, kill and digest pathogen
What are the types of cells for innate immunity?
-dendritic cell
-neutrophil
-macrophage
Adaptive immunity
-focused attack on specific pathogen
-Antibodies (from plasma cells) and cytotoxic T cells help clear specific pathogen
-response requires several days
-lots of control mechanisms
What are the primary effector cells for adaptive immunity?
-Lymphocytes
What are the types of cells for adaptive immunity?
-B and T lymphocytes
Is adaptive pre or post exposure and what cells are used for memory?
-after exposure
-Postexposure immunity by B and T memory cells in common
What are the types of barriers to infection?
-pharynx
-skin
-stomach acidity
-urinary tract
-lysozyme
-normal microbiota
-epithelial cells
What immune system are barriers apart of?
-innate immune system
What are other ways the body prevents infection?
-Mucus and cilia line the trachea moving microorganisms out of body
-mucus, antibacterial peptides, and phagocytes in lungs prevent infection
-blood and lymph proteins inhibit microbial growth
-rapid pH change inhibits microbial growth
How do the pharynx and skin prevent infection?
-Removing particles in nasopharynx
-Skin is a physical barrier that produces antimicrobial and anti-bacterial
How do the stomach and urinary tract prevent infection?
- The stomach has an acidity of 2 that inhibits microbial growth, HCL production
-The urinary tract flushes out
How do the lysozymes and normal microbiota prevent infection?
-Lysozyme in secretions dissolve bacteria wall (gram positive)
-Normal microbiota compete with pathogens in gut and on skin
How do the epithelial cells prevent infection?
-inhibit pathogen invasion and infection
Are organs like the lungs and stomach effect by outside organisms?
-Yes, because they are outside
What are the 2 circulatory systems of the immune system?
-circulatory (blood)
-Lymphatic (lymph) systems
endothelial cells
-line the inner surface of the blood vessels
What does the lymphatic system do?
-fluid balance, immune defense, and fat absorption
-allows fluid out of blood, into tissue, and back into blood.
Leukocytes
-white blood cells
-fight infection
-inflammation
-B cells produce antibodies
-tissue repair
-phagocytosis
Erythrocytes
-red blood cells
-transport oxygen from lungs to tissue
-remove carbon dioxide from tissue to be exhaled by lungs
-acid-base balance
-blood thickness
-gas exchange
What are parts of the lymph system that?
-thoracic duct
-lymph node
-spleen
-bone marrow
-MALT = mucosal associated tissue
How does a lymph node work?
-antigens go into B cell
-goes through t-cell
-goes through plasmid
-antibody come out
Detail definition of Innate immune system
-The body’s built-in ability to recognize and destroy pathogens
-Is relatively non-specific for pathogen type, but does recognize some specific pathogen-associated molecules
-Does not require prior exposure to a pathogen, and does not provide memory for better response to repeated exposure to a pathogen.
Detailed definition of Adaptive immune system
-The bodies acquired ability to recognize and destroy pathogens
-Is very specific in recognizing defined molecular markers on individual pathogens
-does require prior exposure to a pathogen and does provide memory for better response to repeated exposure to a pathogen
What cells primarily carry out adaptive immunity?
-T and B cells that produce antibodies to mark pathogens for destruction
Lymphocytes =
T and B cells
What cells are part of the innate immunity?
-phagocytosis
-inflammatory response
-cell-mediated inflammatory
What cells are apart of phagocytosis?
-Antigen presentation
-neutrophil
What cell is apart of the inflammatory response?
-mast cell
What cells are apart of the cell-mediated immunity?
-natural killer cell
-T-cell
What cells are apart of antigen presenting cells?
-Dendrite
-Macrophage
What cells are from monocyte (circulate in blood)?
-Dendrite
-Macrophage
What cells are from Granulocytes (mean and nasty)?
-neutrophil
-mast cell
What cells are from lymphoid precursor?
-natural killer cell
-T-cell
What type of cells are apart of the adaptive immune system?
-cell-mediated immunity
-antibody mediated immunity
What cells apart of antibody mediated immunity?
-plasma cell
What cell is from B-cell?
-plasma cell
What are the two main phagocyte cells?
-Neutrophils
-Monocytes
Neutrophils
-polymorphonuclear leukocytes (PMNs)
-negative charge, profession
Monocytes
-give rise to macrophages and dendrite cells
What are the jobs of neutrophils and monocytes?
- Engulf, digest, and destroy bacteria
- Process and present antigens to T cell
-only macrophage
Why are bacteria hard to grab?
-because the cell trying to catch bacteria has a negative change and bacteria has a negative charge so they split from each other
Where do phagocytized bacterial end up ?
-inside a phagolysosome (inside vesicle)
What are bacteria killed by?
-Lysozyme
-Oxygen and Nitrogen:
hydrogen peroxide
Nitric acid
Hydroxyl radicals
Why is the phagocyte protected?
-because bacteria destruction takes place within the phagolysosome membrane
What happens to the phagolysosome containing engulfed bacteria?
-Myeloperoxidase
-HOCL- (blech)
How to recognize a pathogen?
-PRR
-PAMP
-Pathogens are marked by antibody binding (requires a prior exposure and adaptive immune response)
What is PRR and what is an example of it?
= pattern recognition receptor (protein) on surface of phagocyte binds to a “PAMP”
-‘Toll-like receptors” are PRRs
What does autoimmune mean?
-When the body attacks its own cells
PAMP
-Pathogen-associated molecular pattern
-molecules commonly found on the surface of a wide variety of pathogens.
-Example: Lipopolysaccharide on Gram-negative bacteria. Peptidoglycan found on surface of Gram-positive bacteria
What are pathogen signals?
-LPS
-PG
-Flagellin
-Teichoic acid
What is the most common cause of bacteria death?
-shock
Process of recognizing a pathogen
-Pathogens with PAMPs
-Binds to phagocyte by activated PRR
-Kills the pathogen
Adaptive Immune Response Characteristics (AIRC)
-memory
-tolerance
-specificity
Memory (AIRC)
-The first antigen exposure induces multiplication of antigen-reactive cells, resulting in multiple copies, or clones.
-After a subsequent exposure to the same antigen, the immune response is faster and stronger due to the large number of responding cells
Specificity (AIRC)
-Immune cells have surface receptors that interact with individual antigens
Tolerance (AIRC)
-Immune cells are not able to react with self-antigen.
-Self-antigen cells are destroyed during development of the immune response
Specific recognition of foreign antigens (AIR)
-Antigens are most commonly proteins or peptides (better), but can be polysaccharides.
What do bacteria coat themselves with?
-a capsule
-capsule is made of sugar
-does not make good antigen
What specifics are antigens recognized by? (AIR)
-T-cell receptor proteins (TCR)
-B-cell receptor proteins (BCR)
-Antibodies
-Major Histocompatibility Complex Proteins (MHC)
What are the antigen-binding proteins? (AIR)
-Antibodies
-T-cell receptor (TCR)
-Major histocompatibility complex (MHC) proteins
=Class I
=Class II
-some proteins bind to many peptides
Generation of diversity in … ? (AIR)
-T-cell receptors
-B-cell receptors
-Antibodies
-MHC proteins
-creates VDJ Recombination
What is VDJ Recombination? (AIR)
-genetic recombination that occurs during cell B and T development
-rearrangement of gene segments of immunoglobulin (Ig) and TCR
-V (variable), D (diversity), J (joining)
-enormous variety
How does the adaptive immune system first ‘see’ an antigen?
-antigen presentation by a phagocyte
-connection between innate and adaptive immune systems
What do viruses do? (AIR)
-float outside cells for a while
-eventually go into a cell
Process of adaptive immune system seeing an antigen intracellular?
-phagocytosis pathogen destruction antigen presenting (APS = macrophage and dendrite)
-MHC I = antigen presenting
-To Tc (T cytotoxic) cell, perforin and granzyme release
-To target cell lysis (lysis infected cells)
Why do Tc cells destroy an entire cell? (AIR)
-Because the virus gets into the cell and there in no way to kill it in the cell and the cell
-So kill the entire cell including the virus
Process of adaptive immune system seeing an antigen extracellular?
-phagocytosis pathogen destruction antigen presenting (APS = macrophage and dendrite)
-MHC II = antigen presenting
-To Th (T helper) 1 cell, cytokines
-cytokine is released
-Inflammation
What do a Th cell do? (AIR)
-helps make antibodies by activating B cell (humoral immunity)
Where are most bacteria? (AIR)
-extracellular
Can antibodies get into a cell? (AIR)
-No, antibodies are limited to extracellular
Antigen Presentation Facts (AIR)
-Major histocompatibility complex (MHC) function as antigen-presenting molecules
-Antigen presenting cells (APC) process antigens and present them onto cellular surface packaged together with MHC molecules
-TCR of a selected T cell can bind only to a complex of foreign antigen presented by MHC complex.
Can T cells interact with foreign antigens? (AIR)
-T cells do not interact with a foreign antigen unless it is presented in the context of the MHC protein
When do T cells do anything? (AIR)
-when they are signaled by antigen presenting cells
shock = (AIR)
inflammation
What are the two types of Major histocompatibility complexes? (AIR)
-Class I MHC = on surface of all nucleated cells in the entire body.
-Class II MHC = on macrophages, dendritic cells, and B lymphocytes (all are phagocytic cells)
T helper 1 cells - Cell-mediated Immunity (AIR)
-TH1
-recognize a phagocyte that is expressing a foreign antigen in the context of a Class II MHC molecule.
-In response they release cytokines and chemokines to further stimulate the phagocytic response
Process of antigen presenting cell to T helper 1 cells - cell-mediated Immunity (AIR)
-Antigen presenting cell
-li protein comes out of ER and binds to MHC II
-breaks into phagolysosome
-Endocytosis = external foreign protein
-peptide binds to MHC which is specialized to each peptide
-binds to surface, CD 4, and activated TH cell
Process of to Macrophage T helper 1 cells - cell-mediated Immunity (AIR)
-Th1 inflammatory T cell
-TCR, antigen, CD4 and MHC II bind to TH1 and macrophage
-release of cytokines
-cytokine activation (activated macrophage)
-Increased phagocytosis of all pathogens
-Inflammation!
Cytotoxic T cell - Cell-mediated Immunity (AIR)
-Tc recognize ANY host cell that is expressing a foreign antigen in the context of a Class I MHC molecule and they kill that cell
-This is important for combatting virus-infected cells and cancer cells
Process of Target cell to Cytotoxic T cells - cell-mediated Immunity (AIR)
-Internal foreign protein go through proteasome turn to peptide
-peptide go through TAP
-go through ER and bind to Class I MHC, chaperone, and B2m
-MCH I and TCR bind to surface of Tc cell with CD8
Process of Cytotoxic T cell to cell death - cell-mediated Immunity (AIR)
-Tc cytotoxic T cell has granules with perforins and granzymes
-TCR, antigen, CD8 and Class I MHC bind to infected cell
-Release of granule contents punches hole in infected cell
-cell death by apoptosis
B Cells - Antibody-Mediated Immunity (AIR)
-B cells express antibodies on their surface as B-cell receptor proteins
-If the receptor binds a foreign antigen, it is taken up and expressed on the cell surface in the context of a MHC II complex
Process of B Cells - Antibody-Mediated Immunity (AIR)
-Antigen reactive B cell uptakes and degrades pathogen
-B cell has antibody receptors
-MHC II, pathogen antigen and TCR bind to B cell and TH2 cell (antigen presentation)
-TH2 cell has cytokines
-cytokine activation of B cell bc of binding to receptors
-B cell forms plasma cell
-plasma cell produces antibodies
How many antibodies does a B plasma cell produce? (AIR)
-1, one B cell makes one type of antibody bc of control
T Helper 2 Cells - Antibody-Mediated Immunity (AIR)
-TH2
-recognize a B-cell that is expressing a foreign antigen in the context of a Class II MHC molecule.
-In response they release cytokines to activate the B cell to divide repeatedly and form antibody-producing plasma cells
-process same as B cell
Antibody-Mediated Immunity (AIR)
-activated cells produce not only plasma cells, but also Memory cells that remain in the body for many years
-Upon a later exposure to the same antigen, a very rapid response (from memory cell) and increase in antibody production results
Process of Antibody-Mediated Immunity (AIR)
-T-helper cell (TH2) binds to T cell receptor, processed antigen, and class II MHC and binds to Antigen processing by B cell
-release of IL-4 and IL-5 cytokines by TH2 cell
-Antigen processing by B cell has antibody with bound antigen
-go to either plasma cell or memory cell
Process of Antibody-Mediated Immunity when it goes to plasma cell (AIR)
-short lifetime
-antibody secretion
-makes a lot of antibodies
what are antibodies?
-Large proteins
Process of Antibody-Mediated Immunity when it goes to memory cell (AIR)
-long lifetime
-second exposure to antigen so quickly converts memory cell to plasma cell
-produces a lot of antibodies
Antibodies/Immunoglobulins
-proteins
-heavy and light chains
-all have an antigen variable and contest regions
-disulfide bonds
-Y-shaped
Why are Antibodies/Immunoglobulins Y-shaped?
-able to bind to 2 bacteria at a time
-cross link them together
IgG, IgA, and IgD Antibodies/Immunoglobulins
-have 2 constant regions and 2 antigen region binds
IgM and IgE Antibodies/Immunoglobulins
-have bigger constant region
-3 constant region and 2 antigen binds
IgM Antibodies/Immunoglobulins
-10 antigen binding sites
-shaped like a ball
-linked 5 receptors together
-linked with J-chain
-disulfide bons
-usually first antibody to be made
Secreted IgA (SIgA)
-4 antigen binding sites
-outside in mucus membrane, most others in circulate in blood
-linked with J-chain
Antibodies/Immunoglobulins Functions
-Toxin Inhibition (Neutralizing antibody) =Tetanus
-Inhibition of interaction of virus with host cell (Neutralizing antibody) = COVID
-Killing of virus-infected cells
-Bacterial pathogen targeting
What are the types of bacterial pathogen targeting?
-Complement activation
-Opsonization (increased phagocytosis) =Coat it with a protein
Complement activation
-A series of proteins that interact with antibody-antigen complexes
-Can cause lysis/destruction of bacterial cells
-will increase phagocytosis (Opsonization)
What are the types of complement activation?
-Classical
-Mannose-binding lectin
-Alternative
Classical complement activation
-antibodies bind to cell surface antigens on bacterium
-C1s, C1r, and C1q bind to antibodies
-Then C2 and C4 bind
-Then C2 spilt into C2a and C2 b
-Then C4 split into C4a and C4 b
-C5 and C3 bind
-Then C3 a and C5a spilt off
-MAC (membrane activated complex) is made and punches a hole in bacteria to kill it
Mannose-binding lectin complement activation
-MBL bind to mannose on bacterium surface
-C2, C3, and C4 bind to complex
-will form a MAC
Alternative complement activation
-B, C3b and D bind to bacterium surface
-D turns to P
-C3 binds
-C3a and C3b spilt off
-forms a MAC complex
Antibody-mediated (humoral) Immunity: Vaccination
-Primary response (1st shot): from antigen exposure to antigen reexposure antibodies made are low
-After reexposure/ secondary response/ booster shot antibodies made are very high and slow decline in immune response
Immune Response:
As a result of immune memory, antigen reexposure triggers a much stronger secondary response
Types of Vaccinations/Immunizations
-Killed bacterial cells/Inactivated virus (good for making antibodies)
-Live attenuated cells/virus (cell-mediated immunity)
-Toxoid=Inactivated toxin protein
-Recombinant/Synthetic antigen
What vaccines should all ages get?
-Influenza
-Tetanus
-Varicella (chicken pox)
What vaccinations are required for all VT students?
-MMR (Measles, Mumps, Rubella)
-Tetanus/Diphtheria (DTaP)
-Meningococcal vaccine
-Hepatitis B
-Polio
-COVID
Relationship between Innate Response and Adaptive Response
- Innate immunity
- Antigen-specific antibody-mediated immunity
- Cell-mediated immunity
