Immunology Flashcards
First line of defense
- Nonspecific; innate
- Any barrier that blocks invasion at the portal of entry
- Not considered a true immune response because it does not involve recognition of a specific foreign substance but is very general in action.
Second line of defense
- Nonspecific; innate
- More internalized system of protective cells and fluids that includes inflammation and phagocytosis
- Acts rapidly at both the local and systemic levels once the first line of defense has been bypassed
Third line of defense
- Highly specific; not innate
- Acquired on the individual basis as each foreign substance is encountered by white blood cells called lymphocytes
- The reaction with each different microbe produces unique protecting substances and cells that can come into play if that microbe is encountered again
- Provides long-term immunity
Immunology:
- The study of all features of the body’s second and third lines of defense
- The study of the body’s response to infectious agents
- The study of allergies and cancer
Types of barriers of the first line of defense:
Physical
Chemical
Genetic
What is a lysozyme?
An enzyme that hydrolyzes the peptidoglycan in the cell wall of bacteria; an additional defense in tears and saliva
“Self”:
“Nonself”:
Self: body cells
Nonself: foreign material in the body such as an invading bacterial cell
The cells of the immune system constantly move and search for potential pathogens. This process is carried out primarily by ______________
White blood cells
Markers:
- Certain molecules on the cell surface that allows cells of the immune system to identify whether or not a newly discovered cell poses a threat
- Generally consisting of proteins and/or sugars
Whole blood consists of:
- Blood cells (formed elements)
- Plasma (clear, yellowish fluid)
- Serum (same as plasma but it is the clear fluid from clotted blood; used in immune testing and therapy)
White blood cells are also called:
Leukocytes
Types of defense mechanisms in the second line of defense:
Phagocytosis
Inflammation
Fever
Antimicrobial proteins
Three main types of (professional) phagocytes:
Neutrophils
Monocytes
Macrophages
Neutrophils:
- A type of phagocyte
- General phagocytes that react early in the inflammatory response to bacteria and other foreign materials and to damaged tissue
Monocytes:
- Transformed by various inflammatory mediators into macrophages
- Roam in blood
Histiocytes:
Specialized macrophages that live in a certain tissue and remain there during their life span
Macrophages:
- Roams in tissue
- Examples: alveolar macrophages; the Kupffer cells in the liver; dendritic cells in the skin; and macrophages in the spleen, lymph nodes, bone marrow, kidney, bone, and brain
Events of phagocytosis:
Chemotaxis Ingestion Phagolysosome formation Destruction Excretion
What happens in chemotaxis?
Chemotaxis: phagocytes migrate into a region of inflammation with a deliberate sense of direction, attracted by a specific chemical stimulus given off from host tissue at the site of injury
PAMPs:
Pathogen-associated molecular patterns: signal molecules on the surface of foreign calls shared by many microorganisms but not present in mammals
PRRs:
Pattern recognition receptors: signal molecules on the surface of phagocytes, dendritic cells, endothelial cells, and lymphocytes that recognize and bind PAMP’s
Inflammation signs and symptoms (Latin) terms and meanings:
Rubor (redness): caused by increased circulation and vasodilation in the injured tissues
Calor (warmth): heat given off by the increased flow of blood
Tumor (swelling): caused by increased fluid escaping into the tissues
Dolor (pain): caused by the stimulation of nerve endings
Why can the inflammation process also be harmful?
- It can cause tissue injury, destruction, and disease
- Many disease-causing microbes have developed mechanisms that elicit inflammation that causes tissue damage (so microbes don’t have to do it themselves)
Cytokines:
Small, active molecules constantly secreted to regulate, stimulate, suppress, and control cell development
The major functional types of cytokines:
- ones that mediate nonspecific immune reactions such as inflammation and phagocytosis
- ones that activate immune reactions during inflammation
- vasoactive mediators
- ones that regulate the growth of activation of lymphocytes
- hematopoiesis factors for WBCs
- miscellaneous inflammatory mediators
A common sign of bacterial infection is a high count of ___________ in the blood
neutrophils
called neutrophilia
Primary component of pus:
neutrophils
Diapedesis:
The migration of WBCs out of blood vessels into tissues
Pyogenic:
Examples of pyogenic bacteria:
Pus-forming bacteria
ex. streptococci, staphylococci, gonococci, meningococci
Pyrogens:
Circulating substances that reset the hypothalamic thermostat to a higher setting
“fever-causing”
2 classifications of pyrogens and description:
- Exogenous: coming from outside the body; come from viruses, bacteria, protozoans, fungi, blood, blood products, vaccines, injectable solutions
- Endogenous: originating internally; liberated by monocytes, neutrophils, and macrophages during the process of phagocytosis (and are natural in immune system)
Benefits of fevers:
- Inhibits multiplication of temperature sensitive microorganisms
- Impedes nutrition of bacteria by reducing availability of iron
- Increases metabolism and stimulates immune reactions and naturally protective physiological processes.
- Speeds up hematopoiesis, phagocytosis, and specific immune reactions
Fever:
Name the types.
Abnormally elevated body temperature that is nearly universal
- Low grade: 100-101
- High grade: 104-106
Hematopoiesis:
The production of blood cells
Stem cells:
Primary precursors of new blood cells are pools of pluripotential stem cells in the marrow
-They proliferate and differentiate
Bacterial PAMPs:
peptidoglycan and lipopolysaccharide
Chief functions of inflammation…
- to mobilize and attract immune components to injured spot
- to set in motion mechanisms to repair tissue damage and localize and clear away harmful stuff
- destroy microbes and block their further invasion
Fevers of unknown origin (FUO):
- intermittent fever greater than 38˚C (101˚F)
- lasting longer than 3 weeks for no known cause can be determined after 1 week inpatient investigation
Side effects of fevers:
- Tachycardia: rapid heart rate
- Tachypnea: elevated respiratory rate
- lowering of seizure threshold
Interferon:
a small protein produced naturally by certain white blood and tissue cells
Interferon alpha and beta are produced by…
lymphocytes, fibroblasts, and macrophages
Interferon gamma is produced by…
T cells
Biological activities of interferon:
- bind to cell surfaces and induce changes in genetic expression (exact results vary)
- all 3 IFNs can inhibit the expression of cancer genes and have tumor suppressor effects
IFN alpha and beta stimulate…
phagocytes
IFN gamma is the immune regulator of…
macrophages and T and B cells
What signals the cell to produce interferon?
Binding of viruses and other microbes to receptors on a host cell
Interferon are not _________ specific
microbe
How many blood proteins in “complementing” work in concert to destroy bacteria and certain viruses?
26
Cascade reaction:
- sequential physiological response
- first substance in a chemical series activates the next substance, which activates the next, then the next…..
What are the three pathways distinguished by how they are activated but have same end result?
- Classical pathway: initiated either by the foreign cell membrane of a parasite or a surface antibody
- Alternative pathway: activated when components of the complement pathway recognize and bind to pathogen membranes
- Lectin pathway: mannose binding proteins (lectins) must bind to mannose residues on the surface of pathogens in order for the pathway to proceed
Overall stages in the Complement Cascade:
- Initiation: C1 components bind to an initiator bound to a foreign cell
- Amplification and cascade: C1 leads to C5 being cleaved and bound to the membrane
- Polymerization: C5 product becomes the site for the assembly of the membrane attack complex
- Membrane attack: C5-C9 form the membrane attack complex that punctures pores in the cell membrane, leading to lysis
Which pathway is quicker than the classical pathway?
Alternative pathway
Humans and bacteria require ______ for their enzymes.
Iron
Why do iron-binding proteins keep available iron bound so closely?
So it cannot be used by bacteria
Iron-binding proteins and where they are found:
- Hemoglobin: found in RBC
- Transferrin: found in blood and tissue fluids
- Lactoferrin: found in milk and saliva
- Ferritin: found in every cell type
- Siderophores: produced by bacteria and are capable of scavenging iron from iron-binding proteins
What iron-binding protein binds iron more tightly than human proteins?
Siderophores
Antimicrobial proteins…
- are short proteins of 15-20 amino acids
- are able to insert themselves into prokaryotic membranes kill microbes
Antimicrobial proteins have names like…
defensin, magainin, protegrin
What is the membrane attack complex?
C5-C9 forms the membrane attack complex that punctures pores in the cell membrane and leads to lysis
What are lymphocytes?
B cells and T cells
Immunocompetence:
the ability of the body to react with countless foreign substances
Antigens (immunogens):
molecules that stimulate a response by B and T cells
Two features/keys that characterize the specific immune system:
Specificity and memory
Specificity and memory:
- it will respond specifically to certain invader
- it will remember that specific invader and will be quicker to fight it off
Major Histocompatibility Complex (MHC):
- One set of genes that codes for human cell markers or receptors
- found in all cells EXCEPT Red Blood Cells
B cells…
mature in specialized BONE marrow sites
T cells…
mature in the THYMUS
All cells have a variety of different markers on their surfaces for…
detection
recognition
cell communication
MHC Class 1 genes:
- Code for markers that appear on all nucleated cells
- Display unique characteristics or self
- Allow for recognition of immune reactions
MHC Class 2 genes:
- Also code for immune regulatory markers found on macrophages, dendritic cells, and B cells
- Involved in presentation of antigen to T cells
MHC Class 3 genes:
Encode proteins involved with the complement system
Class 1 MHC molecules are found…
on cells with a NUCLEUS
Class 2 MHC molecules are found…
B cells, macrophages, dendrite cells; for presenting antigens
Class 3 MHC molecules are found…
complement system
B cells have receptors that bind…
antigens
T cells have receptors that bind…
antigens that have been processed and complexed with MHC molecules on the presenting cell surface
Clone:
group of genetically identical cells; some are memory cells that will ensure the future reactivity to a specific antigen
The three functional types of T cells:
- Helper T cells
- Regulatory T cells
- Cytotoxic T cells
Helper T cells:
Regulatory T cells:
Cytotoxic T cells:
- Helper T cells: activate macrophages, assist B-cell processes, and help activate cytotoxic T cells
- Regulatory T cells: control the T-cell response
- Cytotoxic T cells: lead to the destruction of infected host cell and other “foreign” cells
T cells produce/secrete…
Cytokines.
-but they do NOT produce antibodies
B cells secrete…
antibodies (receptors) or immunoglobulin (receptors of these cells that bind to antibodies)
Clonal selection:
the exactly correct B or T cell is activated by an incoming antigen
Clonal deletion:
if there’s a receptor that matches “self”, it is deleted so it can’t attack us
Clonal expansion:
the rapid multiplication of B or T cell clones after activation by an antigen
Autoimmunity:
loss of immune tolerance through the survival of “forbidden clones”
CD3 receptors…
surround T cell receptor and assist in binding
CD4 receptors…
accessory receptor proteins that bind to MHC 2 molecules
CD8 receptors…
found on cytotoxic T cells and bind to MHC 1 molecules
Finished protein structure…
Variable region: areas of versatility from one clone to another
Constant region: amino content doesn’t vary greatly from one antibody to another
Epitope:
- the portion of an antigenic molecule to which a lymphocyte responds
- primary signal to the immune system that the molecule is foreign
Haptens:
- small foreign molecules that are too small by themselves to elicit an immune response
- this incomplete molecule links to a larger carrier molecule = immunogenicity
- serves as the epitope
Examples of haptens…
- drugs
- metals
- household chemicals
Alloantigens:
Superantigens:
T cell stimulators
Allergens:
antigens that evoke allergic reactions
How many different combos of gene codings exist for antigen binding sites?
around 10 trillion
First encounter with an antigen is called…
sensitizing event
Plasma cells are produced by what cells?
B cells
Opsonization:
marks antigens for phagocytosis and puts “handles” on objects to get a better grip
Four stages of the immune response:
Stage 1: Development of lymphocyte diversity
Stage 2: Presentation of antigens
Stage 3 and 4: T-cell response and B-cell response
