adaptive immunity Flashcards
adaptive immunity
-targets specific pathogen
-acquired thru infection of vaccination
consists of first and second response
Humoral immunity
- produces antibodies (immunoglobulin) that combat antigens
- B cells = lymphocytes that are created and mature in bone marrow –> recognize antigens and make antibodies
- fight invaders outside cell
cellular immunity
- produces T lymphocytes –> recognize antigenic peptides processed by phagocytic cells–> mature in thymus
- T cell receptors on T cell surface contact antigens, causing T cells to secrete cytokines or to kill presenting cell
- attack antigens that have already entered cell
cytokines
- chemical messengers produced in response to a stimulus
1. interleukins = cytokines bt leukocytes
2. chemokines = induce migration of leukocytes
3. interferons = interfere with viral infections
4. tumor necrosis factor alpha = involved in inflammation of autoimmune diseases
-overproduction = cytokine storm
antigens
- substances that cause production of antibodies
- usually component of invading thing
- can be protein, polysacchride, nucleoprotein, or glycoprotein
- usually on surface –> cell wall, pili, outer membrane, or flagella
- nonpathogenic antigens = pollen, egg whites, blood cell proteins
- epitopes = region that antibodies react with
antibodies
- globular proteins called immunoglobulins
- super specific protein
- reacts with epitope of antigen
- 4 protein chains form Y shape –> 2 identical light chains and 2 heavy ones
- variable regions on end of arms bind epitopes
- constant region is stem which defines class
IgG
- monomer
- 80% of serum antibodies
- in blood, lymph, and intestine
- cross placenta, trigger complement, enhance phagocytosis, neutralize toxins + viruses, bind pathogens
- 1/2 life = 23 days
IgM
- pentamer made of 5 monomer held with J chain
- 6% of serum antibodies
- remain in blood vessels
- cause clumping of cells + viruses
- first responder to infection, but short lived
- 1/2 life = 5 days
IgA
- monomer in serum; dimer in secretions
- 13% serum antibodies
- in mucous membranes, saliva, tears, and breast milk
- prevent microbial attachment to mucous membranes
- half life = 6 days
- initial line of pecific defense
IgD
- monomer
- 0.02% serum antibodies
- structure similar to IgG
- in blood, lymph, and on B cells
- not really sure what they do
- 1/2 life = 3 days
IgE
monomer
- 0.002% serum antibodies
- on mast cells, basophils, and in blood
- cause release of histamines when bound to antigen; lysis of parasytic worms
- 1/2 life = 2 days
B cells
- from stem cells in bone marrow
- go to lymph nodes of spleen
- each has specific antibodies on its surface
- specific antigen binds to specific AB and stimulates B cell to divide + mature (activated)
- some turn into plasma cells –> secrete more AB to that antigen
- some B cells become memory cells –> long lived and easily activated
- some need reasurance by T helper cells
Major histocompatibility complex
- genes that encode molecules on cell surfaces
- Class I MHC are on membrane of all animal cells and signal “self”
- Class II MHC are on surface of antigen presenting cells and trigger B cells
How can B cells produce so many antibodies?!
Light chain has 200 V genes, 4 J genes, and 1 C gene = 800 combos
Heavy chain has 100 V genes, 4 J genes, and a bunch of C regions = 4800
together they make, like, 4 million combos
Antigen-antibody complex
- tags ferein molecules for destruction
- agglutination = clumping
- opsonization
- antibody-dependant-cell-mediated-cytotoxicity
- neutralization = bind active site
- activation of complement system
Thymic selection
eliminates immature T cells
T helper cells vs Cytotoxic T cells
- activate B cells
- kill infected cells
Cytotoxic T lymphocytes
- Precursors are activated
- recognize and kill self-cells altered by infection
- release perforin and granzymes that induce apoptosis
Apoptosis
- programmed cell death
- cells chop up their genome and their membranes bulge out
- phagocytosed before leakage of contents
Natural killer cells
- granular leukocytes that destroy cells w/o MHC I
- kill virus-infected and tumor cells and attack parasites
- not always stimulated by antigen
- form pores in target cell leading to lysis or apoptosis
Antibody-dependent-cell-mediated cytotoxicity
- protozoans and helminths are too big to be phagocytized
- they’re coated with antibodies
- Immune system cells attach to Fc regions of antibodies
- target cell is lysed by chemicals secreted by immune system cell
secondary response
- “memory” or “anamnestic”
- fast, strong, long lived
- Class switching = initial IgM shifts to IgG, E or A
Antibody titer
relative amount of antibody in serum
-reflects intensity of humoral response
active vaccination vs passive vaccination
- receives antigen that’s modified to not cause disease
- receives ready made antibodies (doesn’t get memory cells from this)
Jenner
- wanted to prevent smallpox
- people who’d had cowpox didn’t get smallpox
- expose ppl to cowpx to prevent small pox
- antibodies for cowpox worked on smallpox
vaccine
a preparation of microbes or parts of microbes used to induce immunity
vaccination/ immunization
a type of artificially acquired active immunity
innoculation
introducing an organism to something
6 types of vaccine
- attenuated = whole agent vaccines
- inactivated = whole agent vaccines
- toxoids
- subunit vaccines
- conjugate vaccines
- nucleic acid vaccines
live attenuated vaccines
- multiply
- weakened pathogen
- closely mimic actual infection
- confers lifelong cellular and humoral immunity
inactivated killed vaccines
- safer than live ones
- don’t multiply
- require repeated booster doces
- induce mostly humoral immunity
Subunit vaccines
-use antigenic fragments to stimulate immune response
- Recombinate vaccines = produced by genetic modification
- virus-like particle vaccines = resemble in tact virus but don’t have genetic material
- Toxoids = inactivated toxins
conjugate vaccines
combines weak antigen with strong antigen as a carrier so that the immune system has a strong response to the weak antigen
DNA vaccines
-use a plasmid injected into cells so that the cell constantly produces the antigen –> capable of causig a strong immune response
Development of new vaccines
- less profitable than medicines
- hard to do without animal tests
- some ppl use plants as a source (soybean with malaria antigen)
- more oral vaccines
- vaccines for chronic diseases
- DNA vaccines
