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Pasteurs Contributions to
ScienceRecognized that chickens became immuneto a bacterial pathogen if injected with aweaken avirulent strain.Developed vaccines against rabies andanthrax
1800- French Government enlisted his helpin their Wine Industrywhy? Showedshowed that the decline in quality was due
to a contaminating microbePasteurization
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Jenner - Smallpox vaccine
Noticed that milkmades that had contracted cowpoxdid NOT get smallpoxTest on an 8 year old boy, injected cowpox into him(NOT very nice) Follwed by exposure to smallpox
Vaccine was invented (latin vacca means cow)
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Vaccines continue
- Louis Pasteur.. Anthrax, Rabies, & Cholera vaccinesdeveloped
Modern vaccines are prepared fromliving,
avirulent microorganisms or killedpathogens, from isolated componentsofpathogens, and by recombinant DNAtechni ues.
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Physical Barriers to Pathogens
Before considering innate and adaptive immunemechanisms, it is worth noting that there are variousnon-immune, natural physical barriers prevententry and/or the establishment of pathogens: skin mucus tears (lysozyme) ciliated epithelial cells low pH in the GI tract
These physical barriers are of great importance inprotecting the host from infection, providing effectivebarriers that can be penetrated by few infectious
agents.
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Innate vs Acquired
ImmunityInnate Immunity Non-specific Born with Always present Available quicklyPhysical and Chemical barriers Skin, mucous membranes,
pH, enzymesCellular Defenses
Phagocytosis andextracellular killingInflammationFeverBiological Active Substances
Acquired Immunity Induced by immunization Adaptive
Highly specificCarried out by activatedlymphocytes T cells and B cells Antigen presentation
interactions b/wlymphocytes andphagocytes
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Acquired Immunity is inducedby Immunization
Active immunization administration of Ag
Passive Immunization transfer of specific Ab from an immunized individual to a non-immunized individual
Adoptive Transfer (Immunization) transferof immunity by transfer of immune cells
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Characteristics of the ImmuneResponse
Specificity ability to discriminate among different molecularentities
Adaptiveness ability to respond to a previously unseenmolecule
Discrimination b/w self and nonself recognition of Agmainly by lymphocyte surface receptors
Memory ability to recall previous contact and mount a morerapid and larger response (anamnestic response)
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In addition to this, several features of immuneresponses, such as memory and specificity , havecaptivated the interest of biologists for many years.
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Cells Involved in the
Acquired Immune ResponseLymphocytes major cellular players in theimmune response (1950)
Three major cell types involved in acquiredimmunity Common lymphoid precursor
T cell matures in the thymusB cell matures in bone marrow
Ag-presenting cells (APC)Myeloid progenitorMacrophages and dendritic cells
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Ag-Presenting Cells (APC)
Do not have Ag-specific receptors as do lymphocytes
Process and present Ag to T cells
Present Ag in context with major histocompatibility complecMHC
MHC molecules responsible for rejection or acceptance oftransplanted tissue
MHC Class I presents to cytotoxic T cells MHC Class II presents to helper T cells
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Other Cell types
Neutrophils and mast cells
Participate in both innate and acquired immunity
Involved in effector phases of the response
No specific Ag recognition function
Activated by cytokines
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Three Phases of Immune
ResponsesRecognition Phase Binding of foreign Ag to specific receptors on
mature lymphocytes
Activation Phase Sequence of events induced in lymphocytes as a
consequence of Ag Recognition All lymphocytes undergo two major changes
Proliferation (amplification)Differentiation
Lymphocyte migration home to sites of Agentry and persistence
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Three Phases of Immune
ResponsesEffector Phase Lymphocytes specifically activated to perform
functions for elimination of Ag Work w/ other non-lymphoid effectors cells
(nuetrophils and phagocytes) Complement lysis and phogocytosis of
microbes
Cytokines Protein hormones secreted by activated TcellsEnhance function of phagocytes and stimulate
inflammation