Chapter 1 - Intro Flashcards
What are some examples of antigens?
- Usually thought of as infectious agent
- Can also be environmental substances
- Can also be synthetic structures
Characteristics:
- Innate or natural immunity
- Available quickly
- Not specific to the pathogen in question
Characteristics:
- Acquired immunity
- Specific
- Reaction to one pathogen doesn’t protect from another
- Large scope
- Lots of invaders can be targeted, some that don’t even exist yet
- Can discriminate
- Can react against what is foreign and not against self
- Has memory
- So an individual is protected by vaccines
What are the structural barriers of the innate immune system (5)?
- Skin
- Cough reflex
- Sneeze
- Mucus, associated cilia
- Ear wax
What are the chemical/bacterial influences of the innate immune system
- Chemical influences
- Acidity
- – sweat (pH 5.6)
- – sebaceous glands
- – vagina (pH 5)
- – stomach (pH 1)
- Lysozyme is an enzyme present in the skin and stomach, tears
- Normal flora
- Prevent other bacteria from growing
- Affected by antibiotics
What are the organs of the acquired immune system (6)?
- tonsil
- lymph node/lymphatics
- thymus
- spleen
- Peyer’s patches
- bone marrow
What cells comprise the blood portion of the innate immune system (3)?
- Granulocytes
- Neutrophils, eosinophils, basophils,
- Monocytes
- Lymphocytes
- Natural killer cells (NK cells)
- Lymphokine-activated killer cells (LAK cells)
What cells are found in the tissue portion of the innate immune system (3)?
- Macrophages
- Mast cells
- Dendritic cells
- What does CD stand for?
- With regards to CD, what do all white blood cells have in common?
- clusters of differentiation: surface markers that differentiate WBCs from each other
- All WBCs are CD 45+
- What CD markers are present on all granulocytes?
- Where do granulocytes get their name?
- CD 45+, CD15+
- Granules in cytoplasm
- Named for their granule staining when stained using Wright stain
What are the three types of granulocytes and how did each of them get their names?
- Neutrophils –neutral staining
- Eosinophils –red staining
- Basophils –blue staining
- When do the granulocytes get to an infection?
- What is the life span in the blood? In the tissue?
- First cells to enter acute infection site
- Short lived: 12hrs in blood, 1-2 days in tissue
What is the role of the neutrophil (3)?
- Active in phagocytosis
- Some involvement in antigen presentation
- Attracted to site of infection by chemotaxins
- What is the role of the eosinophil?
- What % of WBCs are eosinophils?
- Involved in antiparasitic responses and allergic reactions
- Increase in number in these responses
- Make up 1-3% of white blood cells
- What is the role of the basophil?
- When do you see a higher concentration?
- Rarest granulocyte
- Function not completely defined
- May have a role in inflammation and allergy
- May increase in concentration in:
- – leukemia
- – some allergic responses
- – chronic inflammation
- – patients following radiation therapy
Mast cells
- What is the primary role?
- What granules do they release?
- Where in the body are they found?
- Primary role in allergic and antiparasitic reactions
- Have surface receptor for IgE
- Contain granules of histamine and heparin
- Found in tissues, in connective tissues, and near mucosal surfaces
Macrophages:
- What CD cluster is present?
- Macrophages CD14+
Macrophages - names of cells in each of the following locations:
- Blood
- Tissue
- Liver
- Neural tissue
- Connective tissue
- blood: monocytes
- tissue: macrophages
- liver: Kupfer cells
- neural tissue: microglial cells
- connective tissue: histiocytes
Macrophages - names of cells in each of the following locations:
- Bone
- Kidney
- Lungs
- Plaque of atherosclerosis
- bone: osteoclasts
- kidney: mesanglial cells
- lungs: alveolar macrophage or dust cells
- In heart disease in a plaque of atherosclerosis, they are called foam cells
Macrophages:
- % of WBCs
- When do they increase in number?
- What is the life span?
- Make up 4–6% of white blood cells
- Increase in number with inflammation, infection, and certain cancers
- Important in antigen presentation
- Important in phagocytosis of pathogens
- Life span can be several months
Dendritic cells
- What is the CD marker?
- Where in the body in the immature state?
- The mature state?
- What is the primary role?
- CD11c+
- In bloodstream in immature state
- In tissues in mature state
- Very active in phagocytosis and antigen presentation
- How are Natural killer (NK) cells differentiated from other lymphocytes?
- What type of cells/infections do they kill/respond to?
- Unlike other lymphocytes not antigen specific
- Kill tumor cells and virally infected cells
- Can respond to bacterial and protozoal infections
What two methods do NK cells use to kill their targets?
- Make direct contact with their target
- Antibody directed cellular cytotoxicity (ADCC)
- What cytokine surface receptor do NK cells have?
- What does that cytokine do to the NK cells?
- NK cells have surface receptor for the cytokine IL-2
- Form Lymphokine Activated Killer cells (LAK)
- Are more efficient at killing the target
- Used in cancer therapy
What are the three classes of molecules of the innate immune system?
- Pattern recognition receptors
- The molecules produced in response to the infection (cytokines, antimicrobial peptides, and acute phase reactants)
- Complement proteins
Pattern Recognition Receptors (PRRs):
- What are they?
- Where are they found, and what do they do?
- Recognize surface molecules expressed in groups of microorganisms
- On cell surface or as molecules in solution
- Cell surface
- – Involved in phagocytosis and cytokine release
What are the most common Pathogen-associated molecular patterns (PAMPs) (7)?
- Unmethylated DNA
- DNA with increased amounts of CpG
- ds and ss RNA
- Terminal mannose
- LPS
- peptioglycan
- flagellin
Acute Phase Reactants
- Molecular size?
- What role do they play?
- Usually <100 amino acids
- Bind to the cell wall of the microbe
- Increase membrane permeability to kill pathogen
Acute Phase Reactants
- What are the two main families?
- What cells produce them?
- Where in the body are they found?
- Two major families of antimicrobial peptides
- Defensins and cathelicidins
- – Different secondary structures, similar function
- Produced by epithelial cells and phagocytes
- Provide protection at epithelial surfaces
Acute Phase Reactants
- What are they?
- What is the notable test that levels can effect?
- What type of cells stimulate production?
- Proteins whose concentrations change with inflammation
- May cause the inflammation associated increase in erythrocyte sedimentation rate (esr)
- Production stimulated by cytokines
Acute Phase Reactants
- What are some examples (6)?
- C-reactive protein
- alpha-1 acid glycoprotein
- haptoglobulin
- fibrinogen
- serum amyloid A
- complement
What are the three processes of the innate immune system?
- Inflammation
- Chemotaxis
- Phagocytosis
Inflammation:
What is the purpose (4)?
- Brings the response to the infection
- Helps eliminate the infection
- Repairs damage
- Removes any debris caused by the infection or by the response
Inflammation:
- What are the hallmarks?
- What responses does it illicit?
- Hallmarks
- Redness, swelling, heat, pain, sometimes also loss of function
- Responses
- Increases in blood supply and capillary permeability
- Migration of neutrophils then macrophage to site
Chemotactic factors
- What are they (what do they include)?
- What do they do?
- Include complement pathway products, cytokines and other cellular products
- Bring cells to phagocytize invaders
Phagocytosis
- Define
- Process wherein leukocyte engulfs and digests and kills the microbe
Phagocytosis
- How does cell attachment occur?
- PRRs binding to PAMPS
- Opsonins (Greek “to prepare food for”) - makes antigens look “tastier”
- Some pathogens can survive in phagocytic cells and the ride in these cells helps spread infection
What is the cellular part of the innate immune system?
The humoral part?
- Phagocytosis cellular part
- Acute phase reactants humoral part
- What are the cells of the acquired immune system?
- What % of WBCs?
- Nuclear morphology?
- Lymphocyte: T and B cells
- 20% of circulating white blood cells
- Almost all nucleus
Lymphocytes
- What cells do they arise from?
- How do they get their names?
- Arise from hematopoietic stem cells
- Differentiate in primary lymphoid organs to T or B cells
- Named from their location of maturation
- – Mature to become T cells in the thymus
- – In mammals mature to become B cells in the bone marrow
What are the two arms of the acquired immune system?
- Humoral arm
- Antibody mediated immunity
- Cellular arm
- T cell mediated immunity
How do B and T cells recognize antigen?
- through a specific molecule on their surfaces
- B cell
- – This is surface immunoglobulin
- T cells
- – This structure is called the T cell receptor
- Why are the antibody gamma globulins named so?
- How many are there?
- Named gamma because the immunoglobulin moves slower than albumin, alpha 1, alpha 2 and beta globulins
- In serum protein electrophoresis serum proteins separate into 5 proteins
What are the 5 types of antibody molecules?
- IgG
- IgM
- IgA
- IgE
- IgD
Describe the basic structure of an antibody molecule
- Two heavy chains make up the constant region and a portion of the variable region.
- The heavy chains are joined at the constant region by a pair of disulfide bonds.
- Two light chains join the heavy chains and complete the variable region. They are linked to the heavy chains by a single disulfide bond
What triggers the B cells to
produce antibody?
- a response to the antigen specifically binding to the surface immunoglobulin on the B cell
How are B cells characterized?
- by the antibody in response to the antigen specifically binding to the surface immunoglobulin on the B cell
- by the presence of the surface molecules CD 19, 20, 21
- How are the T cells activated?
- What cells are responsible for doing this?
- Respond to antigens bound to their T-cell receptor (TCR)
- Presented by an antigen presenting cell
- In either a major histocompatibility complex (MHC) Class I molecule or MHC Class II molecule
Major Histocompatibility complex
- where did the name come from?
- where do we get them from?
- what role do they serve?
- Named because these antigens discovered due to their role in the rejection or acceptance (compatibility) of tissue (histo) grafts
- Genetically inherited molecules
- Important in antigen presentation and in the immune response
What do B cells become upon antigen stimulation?
- B cells become antibody secreting plasma cells or memory cells with antigen stimulation
What are the three types of T cells and what do they do?
- helper T cells that secrete cytokines, which upregulate the immune response
- cytotoxic T cells that kill target cells after making direct contact with their target
- regulatory T cells, which serve to downregulate the immune response
- What MHC class do helper T cells respond to?
- What MHC class do cytotoxic T cells respond to?
- T helper cells respond to a specific antigen bound to their TCR and the MHC class II molecule of the APC
- T cytotoxic cells respond to a specific antigen bound to their TCR and the MHC class I molecule of the APC
- What MHC class do regulatory T cells respond to?
- cells bind to their specific antigen through their TCR
- In MHC class II molecules of the APC
- Or sometimes in MHC class I of APC
What CD markers do:
- All T-cells have?
- T helper cells have?
- T cytotoxic cells have?
- CD 3 +
- T helper cells are CD 4+
- T cytotoxic cells are CD 8+
- What CD markers do T regulatory cells have?
- What specific marker characterizes these cells?
- Usually CD4+
- CD8+ regulatory cells can also be found
- Foxp3+ serves as the marker that characterizes these cells
What is the difference between the primary and secondary lymphoid organs?
- Primary lymphoid organs: Where lymphocytes mature into T and B cells
- Secondary lymphoid organs: Where lymphocytes meet antigens
Primary lymphatic organs
- What happens to lymphocytes in these organs?
- What happens to antigens in these organs?
- Lymphocytes are generated
- Initial differentiation of lymphoid cells occurs
- Forms mature T cells, B cells, and NK cells
- Antigen contact results in cell death via apoptosis
Primary lymphatic organs
- Bone marrow: what type of cells are produced here?
- Thymus: what type of cells are produced here?
- Bone marrow
- Major site of hematopoiesis after gestation
- B cells and NK cells are produced here
- Thymus
- T cells are produced here
Primary lymphatic organs
- Bone marrow: what are 5 major components?
- Hematopoietic stem cells -can be any blood type
- Macrophages
- Stromal cells
- Connective tissue
- Adipocytes
Thymus
- Morphology & location
- Size throughout life
- A bi-lobed organ below thyroid and over heart
- ~22 grams at birth
- increases to ~ 35 grams at puberty
- After puberty it decreases in size, becomes mostly fat and fibrous tissue
- Largest organ compared to person’s mass at birth
Thymus
- Process of T cell maturity
- sites
- cell types
- pathway
- Lymphoid progenitor cells enter from bone marrow at cortex
- Become immature thymocytes, cortical epithelial cells, and macrophages
- Thymic nurse cells between cortex and medulla
- Help thymocytes mature
Thymocytes
- What CD markers do they begin with?
- What is the first step in their maturation?
- Begin as CD3-, CD4-, and CD8-
- First step in their maturation, T cell receptors develop that have either alpha beta chains or gamma delta chains
Thymocytes
- How much (relative) T cell population do the gamma delta chains make up?
- What will they become?
- What CD markers do they have?
- minor population of specialized T cells
- Will become the T cells of the gut mucosa and the epidermis
- CD3+, but they are both CD4- and CD8-
Secondary lymphoid organs
- What happens with lymphocytes in these organs?
- What brings the antigens to these organs?
- Describe the path of circulation of lymphocytes
- Lymphocytes meet trapped antigen + APCs; Proliferate if it is their Ag (lymphocytes respond to one antigen only)
- Ag brought to lymph nodes by phagocytic cells
- Lymphocytes circulate through lymphatic vessels and secondary lymphatics
- What happens after B and T cells meet their antigen?
- Through what process do they mature?
- B cells make antibody
- T cells making cytotoxic or helper response
- Maturation by somatic mutation
What are the 5 secondary lymphoid organs?
- Lymph nodes
- Spleen
- Tonsils
- Mucosal-associated lymphoid tissue (MALT)
- Skin-associated lymphoid tissue (SALT)
The lymph nodes
- where are they?
- under what circumstances do they increase in size?
- Located where lymphatic vessels meet
- Increase in size brought about by the proliferation of antigen-responsive lymphocytes
What are the three main roles of the spleen?
- Captures antigens from the bloodstream
- A site where lymphocytes in circulatory system meet antigens
- Remove aged red blood cells
Mucosal-associated lymphoid tissue (MALT)
- where located?
- what are two subclasses of MALT?
- Where the inside of the body meets the outside world
- Respiratory-associated lymphoid tissue (RALT)
- Gut-associated lymphoid tissue (GALT)
Skin-associated lymphoid tissue (SALT)
- what type of cells (6) make up SALT?
- Keratinocytes
- Make cytokines
- Antigen-presenting cells
- Natural killer cells
- Mast cells
- Epidermal lymphocytes
