Immunology/Vaccination Flashcards
Immunity
The active ability of an organism to resist infection
Innate immunity
The body’s built-in ability to recognize and destroy pathogens or their products
Adaptive immunity
The acquired ability to recognize and destroy a pathogen and its products
Activated by exposure of the immune system to the pathogen
Immunity results from the actions of cells that circulate through the
blood and lymph
Normal Microbiota helps host resist pathogens, particularly on the
skin and in the gut (competitive exclusion).
Name the physical and chemical barriers to infection
Mucosal membranes are coated with a thick layer of mucus.
Stomach acid inhibits bacterial growth.Skin is salty and acidic, limiting bacterial growth.
The lymphatic system is a
separate circulatory system that drains lymph fluid from extravascular tissues
Blood is pumped through what and returns from the body through what
arteries and capillaries and returns from the body through veins.
In capillary beds
leukocytes and solutes pass from blood into the lymphatic system.
Lymph nodes contain high concentrations of
lymphocytes and phagocytes
0.1 percent of blood cells are
leukocytes.
Leukoctyes include
include phagocytes and lymphocytes
Cytokines influence
the development of stem cells.
Whole blood is composed of
plasma and cells.
Plasma contains proteins and other solutes.
Serum is the portion
of blood that is not cells or clotting proteins.
Lymphocytes are specialized
leukocytes involved exclusively in adaptiveimmune response.
Leukocytes are
nucleated white blood cells.
Name the two types of lymphocytes
B and T cells
B cells
originate and mature in bone marrow.
T cells
originate in bone marrow, but mature in thymus.
Bone marrow and thymus
primary lymphoid organs
Lymphoid stem cells produce
T cells, B cells and NK cells.
Each lymphocyte produces a unique
name each for T and B cell
protein that interacts with a single antigen.
T cells: T cell receptors (TCRs)
B cells: antibodies or immunoglobulins (Igs)
Myeloid cells works
work as part of innate immune response
Antigen presenting cells (APCs) (myeloid)
engulf, process and present antigens to lymphocytes
Monocytes: macrophages and dendritic cells
Granulocytes (myeloid)
contain toxins or enzymes that are released to kill target cells
neutrophils, basophils, eosinophils
Microbial invasion:
bility of a pathogen to enter host cells or tissues, multiply, spread, and cause disease.
Invasion:
ability of a pathogen to enter host cells or tissues, multiply, spread, and cause disease.
Tissue damage triggers
the recruitmentof a large number of phagocytes.
Tissue damage and chemokine release
Resident leukocytes and damaged cells release cytokines, or chemical mediators, that allow communication between white blood cells. (Figure 26.5a)Cytokinesinclude chemokinesand interleukinsare specialized chemokinesRelease of cytokines(general communication) and chemokines(a cytokine that specifically attracts) draws macrophages and neutrophils to the area as they leave circulation (extravasation). (Figure 26.5b, c)
Innate immune response
is the first line of defense
Begins when phagocyte encounters a pathogen or pathogen product
Inflammation can result
Phagocytes
engluf and destory pathogens
Name the phagocytes
Include macrophages, monocytes, and neutrophils
How do phagocytes move
Move by amoeboid action and have lysosomes
Phagocytes recognize a pathogen using
pattern recognition molecules (PRM)
Membrane-bound phagocyte proteins that recognize
pathogen associated molecular patterns (PAMPs)
??? on phagocytes recognize PAMPs
Toll-like receptors (TLRs)
Note: this is different than the antibody-mediated adaptive response
Phagocytic cells use toxic
oxygen to kill ingested bacterial cells by oxidizing key cellular constituents
Explain innate immune response
Membrane-spanning TLR-2 interacts with peptidoglycan from gram+ pathogens. •Interaction stimulates signal transduction, activates transcription factors in nucleus.•Result: transcription of genes that induce inflammation and other phagocyte activities
Phagocytic cells contain bacteriocidal materials
lethal oxidative reactions KNOW THEM
Some pathogens have developed mechanisms for neutralizing toxic phagocyte products
NAME THEM
S . aureus and M. tuberculosis
Some intracellular pathogens produce leukocidins
what is that and what are they
kill the phagocyte (forms pus)
Some bacteria produce a capsule resistant to phagocytosis name a bacteria
S. pneumoniae
Inflammation
is a nonspecific reaction to noxious stimuli
Redness, swelling, pain, and heat localized at site of infection
Molecular producers of inflammation are proteins:
cytokinesand chemokines(produced by phagocytes and lymphocytes i.e. T cells)
Inflammation also
whats the downside
Isolates and limits tissue damage, destroying damaged cells and pathogens
Downside: Inflammation can result in considerable damage to healthy tissue
are the first to arrive at scene of infection
Neutrophils
Attracted to site by
interleukins (a cytokine/chemokine that is released from damaged host cell)
Activated neutrophils release
chemokines to recruit macrophages by guiding them along a chemokine gradient
Usual outcome of inflammation is a
rapid localization and destruction of pathogen
In some cases inflammation fails to
localize pathogen and the reaction becomes widespread
Can lead to septic shock,a life-threatening condition
Septic shock can be
more dangerous than the initial infection
T lymphocytes
recognize peptide or carbohydrate antigens through cell surface T cell receptors (TCRs)
Cell-mediated immunity
leads to killing of pathogen-infected host cells through recognition of pathogen antigens found on infected host cells
Antibody-mediated (humoral) immunity
is effective against extracellular pathogens such as bacteria and soluble pathogen products
Antigens
are substances that react with antibodies or TCRs
T cell receptor (TCR)
is a membrane protein
Each T cell has thousands of copies of the same TCR on its surface
Major Histocompatibility Complex (MHC)
Initially identified as being responsible for immune-mediated organ transplant rejection
Now know they function as antigen-presenting molecules
MHC-I proteins present items from inside cells, found on all nucleated cells, mainly react with cytotoxic T cells
MHC-II proteins present items from inside cells, found only on B lymphocytes, macrophages and dendritic cells (the antigen-presenting cells APCs), mainly react with T helper cells
MHC-I proteins expressed on the
cell surface reflect the composition of the proteins inside the cell
T cells don’t interact with a foreign antigen unless
it is presented in the context of a MHC protein
T-cytotoxic cells (CTLs or Tc)are T cells (T-lymphocytes) that
kill cells displaying foreign antigens (in MHC-I)
T-cytotoxic cells (CTLs or Tc)
contact target; granules contain enzyme that perforates target cell membrane
Other enzymes cause apoptosis
Natural killer cells (NK cells)are not
T cells or B cells
Kill targets in the absence of a specific protein
Natural killer cells (NK cells)
Lack of normal MHCs result in killing
TH1 subset
activates macrophages by secreting cytokines (including interferon gamma and others)
Also play a role in inflammation and transplanted organ rejection
TH2 subset
plays a crucial role in B cell activation and antibody production
Antibodies or Immunoglobulins (Ig)
are protein molecules that interact specifically with antigens
Antibodies or Immunoglobulins (Ig)
Found in serum, milk, and gastric secretions
5 major classes (IgG, IgA, IgM, IgD, andIgE)
is the most common antibody circulating in the body
IgG
IgG
4 polypeptide chains (2 heavy and 2 light chains)
Antigen-binding site results from interaction between heavy and light chains
We all produce billions of different antigen-binding sites
All five classes
have different structural characteristics, expression patterns, and functional roles The heavy chains of a given antibody define its class based on amino acid sequence
Each person can
produce billions of different antibodies and T cell receptors (TCRs)
Antibody production
responds to antigen exposureInvolves interactions between B cells and T cells
Antibody production:
Antigen-stimulated B cells multiply and differentiate to form antibody-secreting plasma cells and memory cells (primary antibody response)
Memory B cells generated may live for years and quickly transform into antibody-secreting cells (secondary antibody response)
Complement
is a group of sequentially interacting proteins
Roles in innate and adaptive immunity
Cause lysis of pathogens or mark them for recognition by phagocytes
Complement lyses
many gram-negative bacteria
Opsonization
A bacterial cell is more likely to be phagocytized if it has been bound by an antibody
Complement binds antibody-antigen complex, increases likelihood of phagocytosis further
Superantigens
Proteins capable of eliciting a strong response because they activate more T cells than a normal immune response
Produced by many viruses and bacteria that interact with TCRs
Superantigen-activated T cells may produce diseases characterized by systemic inflammatory reactions
Natural active immunity
By acquiring an infection that initiates an adaptive immune response
Natural passive immunity
Through antibody transfer across the placenta or in breast milk
Artificial induction of immunity
to individual infectious diseases is a major weapon for the treatment and prevention of diseases
Artificial active immunity (vaccination)
Can be achieved through exposure to a controlled dose of a harmless antigen to induce formation of antibodies
Artificial passive immunity
Can be achieved through injection of an antiserum derived from an immune individual
Immunization
The process of generating an artificial active immune response by exposure to an antigen or antigen mixture (vaccine)
Immunization with live cells or virus is usually
more effective than that with dead or inactivated material
nATURES OF vaccines
The importance of immunizations in controlling infectious diseases is well established, and the Center for Disease Control has specific recommendations for children in the United States. (Figure 28.25)
Immunizations usually involve a series of secondary immunizations or “booster” immunizations to produce a secondary response and a higher antibody titer.
Synthhetic vaccines
Synthetic vaccines are the product of genetically engineering antigenic components to stimulate the immune response.
Conjugate vaccines attach a smaller antigenic protein to a larger carrier protein to improve immune response to the protective antigen.Attaching a polysaccharide to a toxoid improves the immune response of polysaccharides, which are not as immunogenic as proteins.
Pneumococcal vaccines are made this way. (Figure 28.26)
DNA vaccines
Target proteins are cloned into plasmid vectors and injected intramuscularly.
The DNA is taken up by host cells, and proteins are expressed.
The host then mounts an immune response to the protein.
DNA vaccines:
based on expression of cloned genes in host cells
Antiviral drugs
Most antiviral drugs also target host structures, resulting in toxicity
- Most successful and commonly used antivirals are the nucleoside analogs.(e.g., AZT)
- block reverse transcriptase and production of viral DNA
- also called nucleoside reverse transcriptase inhibitors (NRTIs)
Nonnucleosidereverse transcriptase inhibitors (NNRTIs)
bind directly to RT and inhibit reverse transcription.
Protease inhibitors
inhibit the processing of large viral proteins into individual components.
Fusion inhibitors
prevent viruses from successfully fusing with the host cell.
Nevirapine
Nonnucleoside reverse transcriptase inhibitor
•Binds directly to catalytic site of HIV reverse transcriptase
•Inhibits chain elongation
Azidothymidine(AZT) aka zidovudine
Nucleoside reverse transcriptase inhibitor (inhibits virus replication)
- Nucleoside analog missing the –OH group on the 3’-carbon
- Causes nucleotide chain elongation to terminate when analog incorporated
Neuraminidase
Nicks sialic acid to cut loose from the cell (exit)
Hemagglutinin
Holds onto sialic acid to enter host cells
T-cytotoxic (Tc) cells
Recognize the antigen presented by an MHC I protein on an infected cellKill antigen-bearing target cells directly
T-helper (TH) cells
Interact with peptide-MHC II complexes on the surface of antigen-presenting cellsAct through cytokines to promote immune reactions
TH1 cells
Initiate inflammation and immunity by activating macrophage
Antibodies (immunoglobulins)are soluble proteins made by
vB cells in response to exposure to nonself antigens that are part of pathogens or their products
B cells display antibodies on their cell surfaces that directly
interact with antigens to cause B cells to ingest pathogen via phagocytosis
B cells then produce many pathogen-derived
peptide antigens that are presented to antigen-specific TH2 cells
