final Flashcards
active immunity
body is exposed to pathogen and produces its own antibodies (natural: infection, artificial: vaccination)
passive immunity
occurs when we acquire antibodies made my another organism
natural: placenta, breast milk, artificial: gamma globulins, faster and does not generate memory
constant region
on the main tail - determines the mechanism used to destroy the antigen, structural framework, same on the antibody
Fab
the light chain on the tails - the binding fragment - recognizes the antigen, consists of two variable and two constant domains
Fc
he main tail, crystallizable fragment - interacts with other elements of the immune system such as phagocytes or components of the complement pathway to promote removal of the antigen
variable region
on the two tails, antigen specificity of the antibody, binds to the antigen, divalent
IgM
pentamer, associated with primary response, strongly activates the complements, naive B cells, micro heavy chain
IgG
monomer, most abundant isotype in the serum, longest half life (23 days), 4 subclasses (IgG1-4), most IgG cross the placenta (FcRB), opsonin (Fc receptor fetus to placenta), activates complements gamma heavy chain
IgA
mono to tetramer, in external excretions (saliva, intestinal and bronchial mucus, breast milk) alpha chain
IgE
monomer, target parasites and allergen, decorate mast cells, basophils, and eosinophils through FcR, causing degranulation, transportation relies on the Fc fragment
IgD
appear on the surface of B cells, the role is unclear
five physiological functions of antibodies
- antigen clumping (valence) and neutralization
- opsonization
- ADCC
- complement fixation
antigen clumping and neutralization
toxins, control infection, targets of the therapeutic antibodies
opsonization
neutrophils and macrophages *FCgama, IGg - opsonin an antibody or other substance which binds to foreign microorganisms or cells making them more susceptible to phagocytosis.
ADCC
through degranulation of mast cells, basophils, eosinophils and NK (IgE, IgG) - antibody-dependent cell-mediated cytotoxicity, is a mechanism of cell-mediated immune defense whereby an effector cell of the immune system actively lyses a target cell, whose membrane-surface antigens have been bound by specific antibodies.
complement fixation
C3b (potent in opsonization: tagging pathogens, immune complexes (antigen-antibody), and apoptotic cells for phagocytosis) opsonization, degranulation, chemotaxis, MAC (membrane attack complex) (IgM, IgG) - the process of binding serum complement to the product formed by the union of an antibody and the antigen for which it is specific that occurs when complement is added to a suitable mixture of such an antibody and antigen
primary immune response
clonal selection - plasma membrane of naive B cells, IgA, IgB heterodimer to form BCR, BCR binds to specific antigen leading to receptor oligomerization, specific clone of the B cells proliferates, specific clone of the B cell proliferates and differentiates into IgM secreting plasma membranes and memory B cells, activated B cells can undergo isotope switching and differentiate into plasma cells (IgG, Iga, IgE corresponding memory B cells
secondary response
memory cells encounter the same antigen, rapid clonal expansion to effector to effector cells, differentiation into isotope plasma cells, antibody production and secretion, secondary response is faster and stronger
MHC class I
expressed on all nuceated human cells and recognized by cytotoxic t cells - CD8 binding- B2 microglobulin, cytotoxic T cell attack the virus-infected cells
MHC class II
expressed on all antigen-presenting cells (macrophages, B cells, dendritic cells) recognized by helper T cells - CD4 binding, attacks the antigen presenting cells
cTcells attack cells expressing antigen through MHC-I
release pore-forming perforins, release granzymes that activate apoptotic cascade, activate d
helper tcells enhance immunity
secrete cytokines that activate other immune cells (IFNgamma (TH1) interleukins (activation of B cells, mast cells and eosinophils: TH2 activation of cytotoxic T cells (TH1) 2. bind to B cells and promote their differentiation into plasma cells and memory B cells (including class switching) - HIV destroys helper T cells
integrated immune response to bacterial infection
inflammation, components of bacterial cell wall can directly activate complement cascade leading to chemotaxis, opsonization and MAC formation, alert adaptive immune response: antibody-mediated if bacteria are extracellular, activation of helper T cells lead to cytokine secretion and increased b cell clonal expansion antibody production and B and helper T memory cell generation, repair
integrated immune response
humoral and cell mediated, innate and antibody mediated defense (cestracellular - body cells are infectd cytotoxic T cells and NK cells activated macrohages also secrete cytokines (IFN), NK cells recognize some infected cells lacking MHC-I and kill them -
antigenic drift
caused by high mutation rate of viruses, antibodies do not recognize mutated proteins on viruses, annual flu shot
bacteria
prokaryotic (no nucleus), DNA genetic material, have own machinery for replication and metabolism, cell wall and often a capsule that protects against immune cells can be killed or growth inhibited by antibiotics
MOA: cell wall destruction inhibit protein translation, bind ribosomes, B-lactam
viruses are particles
obligatory intracellular parasites, contain either DNA or RNA, nucleic acid is enclosed in a protein capsid, enveloped viruses are enclosed in an outer layer of host membrane and viral host/protiens called envelope, inhibted by anitvirals not antibiotics
virus invades the host cell
endocytosis (non-enveloped), virus envelope fuses with host cell membrane
virus nucleic acid takes over
hid out (herpes simplex type 1) incorporate DNA into host DNA, use host cell machinery to make DNA/RNA and proteins
virus is released
non-enveloped virus causes host cell to rupture - the cell lyses in host cell - enveloped virus particles bud off from the surface
name the tree major functions of the immune system
- protects against pathogens and other immunogens
- recognizes and removes abnormal self cells (cancer)
- removes dead or damaged cells : scavenger cells (macrophages)
innate immunity
born, broad specificity, recognizes pathogen associated molecular patterns, fast response: inflammation, red, warm, swollen, pain, cytokine mediated
acquired immunity
adaptive, immune response at specific pathogens, slow first response, memory, cell-mediated vs humoral (hep B vaccination, infusion of Hep B to a newborn baby to a women with hep B)
immunorecognition
how the body distinguishes which pathogen/what is not
immunogen
chemical compound that triggers an immune response
antigen
chemical compounds that interact with products of the adaptive immune response
epitopes
one of the antigenic determinants of an antigen (one antigen can have several)
haptens
some LMW molecules become immunogenic only when linked to a carrier protein- doesn’t mass to elicit immune response
adjuvants
substances that enhance the immunogenicity of an antigen - enhance the capability of an antigen to initiate an immune response, bigger the molecule more likely it can initiate an immune response
2 lines of defense against pathogens
- physical and chemical- epithelia, gastric acidity, gladular secretions
- internal immune response - detection, cell-to-cell communication with pathogen, chemotaxis, recruitment and coordination, destruction or suppression, depends on the cytokine and antibodies
granulocyte
(polymorphonuclear leukocyte) - has granules, multiple nuclei, degranulation to produce chemicalst to treat/kill pathogens, smaller leukocytes, neutrophil, eosinophil, basophil
what are granules
contain inflammatory mediators that can be released in the cytoplasm
neutrophil
first responder to an infection, 50-70% PBL, most abundant peripheral cell lymphocyte, first responder to a site of inflammation, degranulate and release cytokines, cause fever, highly motile, phagocytic cells, engulf pathogens, short lived, only one involved in phagocytosis
pathway of a neutorphil attack
- recognition- cell-surface receptors invading pathogen
- invagination- cell membrane surrounds microbes and engulfs pathogens
- phagosome formation- cellular granules release contents into vacuole; membrane NADPH oxidase activated
- killing of pathogens- respiratory burst results in a generation of reactive oxygen and produces molecules that destroy all pathogens
eosinophil
inflammatory cells that defend against parasitic infections, 1-3% PBL, migrate in response to chemotactic signals, exhibit a metabolic burst when activated, defend against parasites (release NO and cytotoxic enzymes to kill), increase several fold in response to parasitic infections, also activated by allergens - more specialized in parasitic infections
basophil
release histamine, causing inflammation in allergy and antigen reaction, rare in PBL, recruited to injury, have cell surface IgE, triggers degranulation, releases histamine (vasodilation), heparin (anticoagulant), cytokines, important in allergic/parasitic infection,
mast cells
also bind IgE, similar function to basophils except are concentrated in connective tissues of the skin, lungs, GI
agranulocytes
mononuclear leukocytes, null cell/natural killer cell, mature b cell, helper t cell, suppressor t cell, monocytic cell, lymphocytes, dendritic cell
monocytic cell
migrate from the blood stream and becomes macrophages, 1-6% PBL, circulating monocytes migrate out of the blood vessel, become macrophages, take residence in tissues: liver, brain, bones
macrophages are effective phagocytes
® Neutrophils and macrophages are primary phagocytes
® Macrophages are larger and more effective phagocytes
Macrophages also remove old RBC and dead-neutrophils
Macrophages are antigen presenting cells (APC) in acquired immunity - involved in bigger blood cells
lymphocytes
□ B cells: antigen presentation and antibody production and differentiate into plasma cells and memory cells, derived from the bone marrow
□ T cells: defense against intracellular pathogens, cytotoxic T cells(kills cell containing pathogens - cancer cells) and helper T cell (secrete different mediators- immune resistant)
Natural killer cells (NK cells): defense against intracellular pathogens
dendritic cells
not leukocyte, □ Antigen presenting cells in many tissues (langerhan cells in skin)
□ Recognize and caputre antigens
□ Migrate to secondary lympoid tissues
□ Present antigens to lymphocytes
Antigen binding activates lymphocytes so they can proliferate and come into the blood stream to fight that antigen
primary lymphoid tissue
(immune cell formation and maturation)
Thymus (produces T cells)
Bone marrow (produces other blood cells)
secondary lymphoid tissue
(mature immune cells interact with pathogen and initiate response)
Encapsulated:
Spleen
Macrophages encounter pathogens in the blood
Lymph node
Un-encapsulated (or diffuse lymphoid tissues):
Tonsils
Gut-associated lymphoid tissue (GALT)
Clusters of lymphoid tissues
Strategically positioned
three major classes of immune pathologies
- Immunodeficiencies (under-reaction): Primary immunodeficiency - more genetic, Acquired immunodeficiency (AIDS, HIV) Allergy or hypersensitivity (over-reaction), immune system) Autoimmune disease (mis-recognition) E.g. type 1 diabetes, rheumatoid arthritis
airway physical and chemical barrier
mucocilliary clearance, secretions containing lysozyme and immunglobulins (adaptive)
digestive tract physical and chemical barrier
salivary lysozyme and immunoglobin, gastric acid, intestinal immunoglobulin
genitourinary tract physical and chemical barrier
cervical mucus plug
innate leukocytes
neutrophils, eosinophils, basophils, null cell (NK), monocyte (macrophage)
adaptive leukocytes
b cell, helper t cell, suppressor t cell
pathogen-associated molecular patterns
leukocytes can recognize certain molecules unique to microorganisms - lipopolysaccharide on the outer membrane of gram-negative bacteria, cell wall polysaccharide from fungi, double strand RNA from virus
PAMPs bind to
leukocyte patter recognition receptors and activate leukocytes to kill (degranulation) or ingest (phagocytosis)
toll-like receptors (TLR)
single-pass transmembrane proteins expressed ont he membranes of leukocytes and non immune cells, 10 TLR identified in human, varying in immune cell distrubution and PAMP recognition, TLR link innate and adaptive immunity on dendritic cells
imiquimod
topical cream that treats genital warts, actinic keratoses, basal cell carcinoma, activates TLR7, enhances innate immunity through secretion of cytokines, activate langerhan cells and enhance adaptive immunity - activates NK, macrophages and B lymphocytes, treats HPV and anti-tumor, innate and adaptive immunity
chemotaxins
chemicals that attract leukocyts to the site of infection
chemotaxin examples
- bacterial toxins and cell wall components
- products of tissue injury: fibrin and collagen fragments
- chemotactic cytokines: macrophage chemoattractant protein (MCP-1), IL8
extraversion
leaves blood vessel for tissue
pus
live and dead neutrophils and macrophages, tissue fluid, cell debris, and remnants of immune process