adaptive immunity david, “bubble boy” 1980 from 2011 cbs news 40-year retrospective 2011
TRANSCRIPT
Adaptive Immunity
David, “Bubble Boy” 1980 from 2011 CBS News 40-year retrospective 2011
Innate vs Adaptive immune systems
Innate immune system Adaptive immune system
Response is non-specific Pathogen and antigen specific response
No immunological memoryExposure leads to immunological memory
Found in nearly all forms of life Found only in jawed vertebrates
Immediate, maximal responseLag time of 1-2 weeks after initial exposure
Evolution of the adaptive immune system
Nadia DanilovaMIT OpenCourseWare
Adaptive Immunity: Homeland Security
• What are the detectors and weapons?• How can the adaptive immune system recognize
millions of different molecules it has never before seen?
• How does vaccination confer long-term protection? (immune memory)
Properties of the adaptive immune response: specificity and memory
Campbell & Reece, Biology, 8th ed.
Humoral and cell-mediated branches of the adaptive immune system
• Antibodies produced by plasma (B) cells– Soluble IgG in blood and lymph– Secretory IgA in mucus, tears, milk, saliva– Rarer antibody types: IgM, IgD, IgE
• Cytotoxic T cells attack and eliminate– virus-infected cells– cancer cells– foreign (non-self) cells
Immune specificity: antigen receptors are modular proteins
H
L
V
C
V
C
Antibody = immunoglobulin T-cell receptor complex
How can our cells make over 10 million different antigen receptors?
Antibody and T-cell receptor diversity by combinatorial joining of DNA segments
Immunoglobulins (antibodies): 2 identical heavy chains + 2 identical light chains
heavy chain: V + D + J
light chain: V + J
T-cell receptors: 1 alpha chain + 1 beta chain
alpha chain: V + J
beta chain: V + D + J
Clonal selection theory
• Population of T-cells, B-cells each with own antigen receptor generated by random combinatorial DNA rearrangement
• Antigen binding selects cells to reproduce preferentially
But wait, antigen has to be processed and presented to T-cells!
Class I MHCOn all cellsPresent to CTLs
Class II MHCOn APCs & B cellsPresent to helper T cells
Launching the immune response: antigen processing and presentation
Produces signal moleculesProliferatesProduces memory T helper cells
http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/A/AntigenPresentation.html
Activating antibody production by B cells
APCs
B cells
TH cell
CD4+ T cell
ProliferationDifferentiation of plasma cellsProduction of memory B cells
Activation of cytotoxic T cells
Cytotoxic T cell
Perforin
Granzymes
TCRCD8
Class I MHCmolecule
Targetcell
Peptideantigen
Pore
Released cytotoxic T cell
Dying target cell
Helper T cells assist both antibody production and cytotoxic T cell activation
Campbell & Reece, Biology 8th ed.