Lecture 2 Flashcards
Principles and Components of Immunity
Who discovered that cowpox vaccine also had protection against smallpox?
Edward Jenner in 1796
What term did he coin?
Vaccination: inoculation of healthy individuals with weakened or attneuated strains of disease
What did Metchnikoff discover in 1890?
Many microorganisms can be engulfed by phagocytic cells called macrophages. They are front line components of innate immunity
What is an antigen?
A foreign material that induces response
What is Innate Immunity?
any bacterial pathogen that anyone can relate to
What is adaptive immunity?
Is generated from vaccines
- varies from person to person
- one person getting covid means they have more adaptive immunity for that
Where do the cells of the immune system derive from?
Pluripotent hematopoietic stem cells in the bone marrow
What are the different levels in the bone marrow?
Innate: common lymphoid progenitors and common myeloid progenitor
Adaptive: granulocytes/macrophages, megakaryocyte and erythrocyte progenitor, erythoblast and megakaryocyte
What levels are in the Blood?
Innate: B cell, T cell, NK cell, ILC, immature dendritic cell
Adaptive: neutrophil, eosinophil, basophil, monocyte, platelets, erythocytes
What levels are in the lymph nodes/tissues?
Innate: B cell, T cell, NK cell, ILC, mature dendritic cell
Adaptive: (tissues) immature dendritic cells, mast cell, macrophage
What are in Effector cells in the innate immune system?
B cell -> plasma cell
Activated T cell
Activated NK cells
Activated ILC
What is a pathogen?
Anything harmful causing a disease
What are the levels of defense when a pathogen enters?
Anatomic Barriers
- skin, oral mucosa, respiratory epithelium, intestine
Complement/antimicrobial proteins:
- cascade of proteins to remove pathogen
Innate immune cells:
- macrophages, granulocytes, NK cells, epithelial cells
Adaptive immunity:
- B cells/antibodies, T cells
How long does adaptive immunity take to kick in?
4 days which is why innate response is so crucial. Antigen recognition in adaptive immunity is important and is memory specific
What is the cell mediated immunity process ? (1)
Inflammatory inducers: bacterial lipopolysaccharides, ATP, urate crystals
What is the cell mediated immunity process ? (2)
Sensor cells: macrophages, neutrophils, dendritic cells
- these cells engulf material and are activated by inflammation
What is the cell mediated immunity process ? (3) What is the cell mediated immunity process ? (3)
Mediators: cytokines, cytotoxicity
What are cytokines?
Proteins with immune functions from cells
What is cytotoxicity?
Damage for the cell
What is the cell mediated immunity process ? (4)
Target tissues: production of antimicrobial proteins, induction of intracellular antiviral proteins, killing of infected cells
What are the three phases of immune response?
Innate immune response, Adaptive immune response, and immunological memory
Innate Immunity
Inflammation, complement activation, phagocytosis, and destruction of the pathogen
How long does it take after infection for response to start?
Minutes, and duration is days
What is adaptive immune response?
Interaction between antigen-presenting dendritic cells and antigen-specific T cells: recognition of antigen, adhesion, co-stimulation , T cell-proliferation
What do B cells do in adaptive immune response?
Activation of antigen specific B cells - starts after hours and takes days
What happens to T cells during adaptive immune response?
Formation of effector and memory T cells - starts after days and takes weeks to respond
What happens with the interaction of T and B cells?
The formation of germinal centers, the formation of effector B cells and memory B cells, production of antibody which takes days and takes weeks to respond
When does the pathogen become eliminated?
It becomes eliminated by effector cells and antibodies after a few days
What is immunological memory?
Maintenance of memory B cells and T cells and high serum or mucosal antibody levels - Protection against reinfection which takes days to weeks
What is a chemo kine?
Causes recruitment and is secreted from immune cells
- it leads to migration and follows chemokine gradient moving something from blood to lymph
What is a macrophage and what does it do?
Phagocytosis and activation of bactericidal mechanisms
- antigen presentation and cytokine production
What is an Eosinophil?
Killing of antibody-coated parasites
What is a dendritic cell?
Antigen uptake in peripheral cites due to branching and migratory. It becomes an APC and produces cytokines
What is a basophil?
Promotion of allergic responses
What is a neutrophil?
Phagocytosis and activation of bactericidal mechanisms
What is a mast cell?
Releases granules containing histamines
What do macrophages express that allow them to express different pathogens?
Receptors:
TLR1, TLR2, TLR4, mannose receptor, NOD1, glucan, scavenger receptor
What triggers the inflammatory response?
Infection:
- Bacteria triggers macrophages to release cytokines and chemokines
- Vasodilation and increases vascular permeability cause redness, heat, and swelling
- Inflammatory cells migrate into tissue, releasing inflammatory mediators that cause pain
What are Natural Killer (NK) cells?
Innate cells that partially bridge over into adaptive
- lymphoid cells that lack antigen specific receptors and are part of innate immune system
- circulate in blood as large lymphocytes that contain distinctive granules
- can recognize and kill some abnormal cells, such as tumor cells and virus-infected cells
Where do lymphocytes mature?
In the bone marrow or the thymus and then congregate in lymphoid tissues throughout the body
What initiates adaptive immune responses?
Antigen and antigen-presenting cells in peripheral lymphoid tissues
What are the two major types of lymphocytes?
T cells and B cells
B cells: when activated differentiate into plasma cells that secrete antibodies
T cells: two main classes - one class differentiates into cytotoxic cells which kills cells with viruses
What kind of features do T cells and B cells have
No functional activity until they encounter antigen as well as molecules induced by innate immunity called co-stimulatory molecules
What do T helper cells do?
They make cytokines
What are the parts of an antibody?
Constant region (effector function) which is the bottom of the antibody, and the variable region which is the antigen binding site
What does the structure of the T-cell receptor?
constant region, variable region (antigen-binding site)
Why do we want quaternary or more complex structures for vaccines?
We want to give the full breath of the longer folded protein into the vaccine, so the antibody recognizes that rather than a simple structure.
What is an anamnestic response?
Quicker response to the next exposure of an antigen
What does the course of an immune response look like?
First encounter: produces a primary response, slow to develop
2nd encounter: with the same antigen, produces a very rapid and intense secondary response
- illustrates why we give boost injections after an initial vaccinatio
