Innate and Adaptive Immunity Flashcards
What is the immune system?
tissues, cells, and molecules involved in adaptive immunity
-sometimes the totality of host defense mechanisms
where do all cellular elements of the blood and immune system arise from?
pluripotent stem cells in the bone marrow
Who was the mans that decided to put nasty cow pox on a little boys arm?
Edward Jenner
What are the most common things that cause disease in humans?
virus, bacteria, fungi, protozoa, and worms
What is the innate immune response?
host response to infection which is quick and non-specific
-this is present at birth
What is adaptive immunity?
antigen-specific lymphocytes to antigens
-generated by clonal selection of lymphocytes/ antibody production
When is innate immunity active?
0-4 hours
When is early induced innate response active?
4-96 hours
When is adaptive immune response active?
after 96 hours
What are the major cells of innate immunity?
macrophages, granulocytes (neutrophils), mast cells, dendritic cells, and natural killer cells
What are the major cells of adaptive immunity?
B and T cells
NK cells
plasma cells
How do infections trigger immune response?
-bacteria trigger macrophages to release cytokines and chemokines
-vasodilation and increases vascular permeability cause redness, heat, and swelling
-inflammatory cells migrate into tissue, releasing inflammatory mediators that cause pain
How do dendritic cells initiate adaptive immunity?
-immature dendritic cells reside in peripheral tissues
-dendritic cells migrate via lymphatic vessels to regional lymph nodes
-mature dendritic cells activate naive T cells in lymphoid organs such as lymph nodes
What is the first barrier against most microorganisms and have rapid repair mechanisms if injured?
epithelial (mucosal) surfaces
Are infectious disease common?
no, the body is typically able to resist the infection
How does the mucosal epithelial cells protect against infection?
-goblet cells secrete mucous (protective covering)
-swallowing in mouth and peristalsis in GI tract moves potential pathogens through GI system
-ciliated epithelial cells in upper respiratory tract
-Paneth cells that produce anti-microbial peptides
-various T cells
What is the best studied mucosal immune system?
components of the gut-associated lymphatic tissue
Is mucosal immunity proactive or reactive?
proactive
-uses pre-existing generalized mechanism to clear infection
Is the adaptive immune system proactive or reactive?
reactive
-responds to specific pathogens
What is a type I mucosal surface?
covered by simple epithelium
-express polymeric immunoglobulin receptor (transcytose IgA through epithelial cell)
-allow IgA to interact with the pathogen
-intestine, lungs, and uterus
What is a type II mucosal surface?
covered by stratified squamous epithelium that provides a physical barrier
-oral cavity and vaginal cavity
Is there only mode of transmission for infectious pathogens?
no!
there are many ways
-inhaled droplets, spores, contaminated water or food, and physical contact (and others)
Infection and stages of immune response:
-adherence to epithelium
-local infection, penetration, of epithelium
-local infection or tissues
-adaptive immunity
What are some bactericidal agents produced or released by phagocytes?
-acidification
-toxic oxygen-derived products
-toxic nitrogen
-antimicrobial peptide
-enzymes
-competitors
Three types of mucosal epithelial cells in host defense:
villus types
ciliated epithelium
exocrine glands
What is mucosal microbiota?
-density varies
-generally nonpathogenic and present only in the outer mucous layer
-utilize mucin glycoproteins for energy
What is the mucus layer? (in gut mucosal barrier)
-viscous properties due to mucin glycoproteins
-contains an array of antimicrobial peptides and antibodies
What are goblet cells?
produce secreted gel-forming mucin, glycoproteins, trefoil peptides, and RELM-beta
What do leukocytes and stroma do?
-regulate secretory cell differentiation
-modulate epithelial secretory function
-produce secretory IgA
What are Paneth cells?
produce antimicrobial peptides, lectins, and cytokines
What is the inner mucus layer?
-relatively sterile
-rich in antimicrobial molecules
What is the outer mucus layer?
-non-sterile
-degrading mucos
-microbes utilize mucin carbohydrates for energy
What do plasma cells do?
antibodies
What is called when the antibodies divide a lot?
clonal expansion
Do progenitors give rise to only one specific lymphocyte?
no, the ones they make many that have different specificities
What are the two components of an antibody molecule?
variable region (antigen binding site) and constant region (effector region)
What creates the diversity of lymphocyte antigen receptors?
somatic gene segment rearrangements
What are the light chains of antobodies?
v (variable) and J (joining segment)
-kappa light chain on chromosome 2
-lambda light chain on chromosome 22
What are the heavy chain genes and their location?
alpha, delta, epsilon, gamma, and mu
-on chromosome 14
How many different light chains are there?
290
How many different kappa chain variables are there?
140
How many different gamma chain variables are there?
150
How many different heavy chains can be created?
13,800
How many total different binding specificities are there?
4,002,000
What is the spot that antigens bind to antibody receptors?
epitopes
Process of T cell receptor binding of antigen
-epitope recognized by t cell receptor often burned
-the antigen must be broken down into peptide fragments
-epitope peptide binds to a self molecule, MHC molecule
-t cell receptor binds to a complex of MHC molecuile and epitope peptide
What are the three ways antibodies participate in host defense?
- bacterial toxin -> neutralization -> ingestion by macrophage
- bacteria in extracellular space -> oponization -> ingestion by macrophage
- bacteria in plasma -> complement activation -> lysis and ingestion
What are major histocompatibility complex molecules/receptors?
large loci of DNA that encode genes for cell surface receptors that are essential for adaptive immune response
What are MHC I molecules?
molecules that collect peptides derived from proteins synthesized in the cytosol from viral infections and display those peptides on the cell surface
-single transmembrane spanning domain
What are MHC II molecules?
molecules that bind peptides derived from proteins in intracellular vesicles and display those on the cell surface
-two transmembrane spanning domains
Steps of viral infection using MHC class I receptors:
-virus infects cell
-viral proteins synthesized in cytosol
-peptide fragments of viral proteins bound by MHC class I in ER
-bound peptides transported by MHC class I to the cell surface
What do cytotoxic T cells recognize?
complex of viral peptide with MHC class I and kills infected cells
How do MHC class II receptors work?
-bacteria infects macrophages and enter vesicle, producing peptide fragments
-bacteria fragments bound by MHC class II in vesicles
-bound peptides transported by MHC class II to the cell surface
-antigen bound by B-cell surface receptor
-antigen internalized and degraded to peptide fragments
-fragments bind to MHC class II and are transported to the cell surface
Are immune responses always helpful?
no, they can be harmful
