6. IMUN UTSImmLecture1

8/11/2019 6. IMUN UTSImmLecture1

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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

6. IMUN UTSImmLecture1

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