Immunology Flashcards
What two molecules does inflammation involve?
Macrophages and neutrophils
Describe a macrophage
They have two life cycles. Immature in blood and mature in tissue.
They scout roaming tissue
Involved in acquired immune response
Induce fever
Describe neutrophils
Bacterial specialist
Called by the macrophages
Leave bloodstream and enter tissue
They chase bacteria and secrete nets that trap bacteria. Emzymes destroy bacteria.
Describe phagocytes that targeting bacteria
Macrophages and neutrophils have receptors that bind bacteria. (TLRS)
Bind components of bacterial cell walls
Bacteria can resist by covering their walls with polysaccharide capsules not
Describe systemic inflammation
Sepsis: microbes in the blood
Leaky. Look vessels throughout the body, too much fluid leaves the vessels, drop in blood pressure.
Activation of clotting factors
O2 starvation occurs in both cases. Can lead to lung and kidney failure.
What are the three levels of defense?
Barrier defense: physical, chemical and mechanical: skin, stomach pH
Innate defense: rapid generic response. Does not distinguish pathogens.
Acquired response: slow, tailored for a particular pathogen.
What are the two phagocytic cells involved in inflammation?
Defense proteins called Macrophages and neutrophils
How do phagocytes target bacteria. What can bacteria do to get out if?
They have receptors that target bacteria called TLRS that bind components of bacterial cell walls.
Bacteria can resist by covering their walls with polysaccharide capsule that prevents the binding of the TLRS.
What are the characteristics of acquired/adaptive response
Tailored to an individual foreign substance
Provedes immunity against reoccurrence
Distinguishes self from non self
What are the targets of specific immune reposes?
Extracellular invader: humoral response - release of antibodies
Intracellular invader: cell mediated response- direct attack by immune system cells
What cells are involved in an acquired immune response?
They are all cells that recognize a specific antigen:
T lymphocytes: helper T cells (TH), cytotoxic T cells (TC) and regulatory T cells (Treg)
B lymphocytes– secrete antibodies
Describe antigen presenting cells
Macrophages– Mostly present in phagocytosis
Participate in both innate and acquired response
Dendritic cells– mostly used for antigen presentation. Immature dendritic cells roam tissue and collect antigen by phagocytosis. Mature dendritic cells display antigen for lymphocytes
What are some advantages of immune response
Additional line of defense
Immunity from disease reoccurrence
What are some disadvantages of immune response
Lacquered immune system cd,la are specialized for particular,ar pathogen (only one in 10,000 T cells will respond to a particular antigen) SLOW
How do immune cells communicate
Chemical signal= cytokines and lymphokines– interleukins (IL1)
Cell surface protein major histocompatibility cells (MHC)– HLA is the human version.
What are the two types of MHC proteins and Describe MHC1
MHC1 and MHC2
MHC1 us present on all uncleared cells, works in the disposal of antigen fragments for TC In the cytoplasm of infected cells.
MHC 2 is used in antigen presentation
Describe MHC 2
Is used in antigen presentation and requires processing and display by APC’s
The structure is 2 non identical subunits.
Antigen binds via non-covalent interaction, antigen fragments 13-20 aas long
( MHC cannot bind an Extracellular antigen)
What TH detect?
Short denatured piece of antigen and surroundingMHC
Conformation of MHC groove and binding properties determined by genetics
Describe the steps of antigen processing by APC
AG binding and phagocytosis Fusion with lysosomes Digestion of antigen AG fragment binds MHC-2 in vehicle AG display on cell surface (TH)
What is a limitation of MHC
Can’t bind all ranges of antigen
Certain pathogen may not bind certain MHC– greater susceptibility of individual to a disease
Describe helper t-cells(TH)
They are produced in the bone marrow and mature in the thymus
Used in antigen recognition using a TCR
CD4 co receptor is an addition protein associated with helper T cells that binds MHC 2
Describe TCRs. What cell are they associated with?
TH Cells
Made of 2 non-identical polypeptide
Each individual T cell has 1 type of TCR
TVR recognizes antigen fragment bound in MHC2
Describe B CELLS
Produced in bone marrow
They generate antibodies– immunoglobulin
Immunoglobulin most common antibody in immune response
5 different constant regions each with their own roles
What area the two regions of an antibody?
The top is the variable region: antigen binding fragment
The bottom is the constant region.
Describe antigen antibody binding.
Antibody recognizes and binds 5 to 6 sugars of amino acids–epitope antigenic determinant
A single protein coups have many antigenic determinants
Describe epitopes
Could be generated by primary through quart nary structure.
Describe native B cells
In G0
Has a transmembrane antibody on surface
Each B cell produces antibody that recognizes only one epitope
Exposure to AG activates only B cells with matching ab– colonial selection
B cell detects Extracellular “free floating” whole antigen.
Describe memory B cells
Ilona lived in G0
Resemble native B cells but there’s more of the,
Activated more easily than native B cells
Describe plasma B cells
They are an antibody secreting factor
They are short lived- only about 4 weeks
Macrophages neutrophils and dendritic cells have Fc receptor
What’s the difference between response time in primary and secondary antibodies
secondary response is much quicker and stronger
What are the two strategies for vaccines?
Active: harmless form of antigen: whole thing killed or weaker
Passive: pre made antibodies
Describe cytotoxic T cells
Function: detect and destroy infected cells
AG recognition: TCR and CD8 co receptor
AG fragment the displayed by MHC1: 2 polypeptides one transmembrane and 1 Extracellular
Ag fragment is 8-19 aa
MHC 1 displays AV from cytoplasm of cells
What is the life cycle of a TC cells
Native and activated
Describe a native TC cells I
Ag mhc1 complex recognizes TCR and CD8
Co stimulation
Cytokines from TH or licensed dendritic cells– TH activates dendritic cell to produce TC activating signals( TH doesn’t need to be present)
Describe activated TC cells
Ieffecotr TC cells are activated
Memory TC cells activated
What area the two killing strategies of TC cells
1– express FAS ligand on membrane
2– secrete cytotoxic so upon contact with infected cells
- perforin assembles unites in membrane to create price for 2nd cytotoxin
- granzyme a protease that directly cleaves procaspase 3
