BIO 351 FINAL EXAM REVIEW QUESTIONS AND CORRECT DETAILED / VERIFIED ANSWERS LATEST UPDATE

BIO 351 FINAL EXAM REVIEW
QUESTIONS AND CORRECT




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DETAILED / VERIFIED

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ANSWERS LATEST UPDATE
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,What is Immunology

•Study of host defense system
ºInvolved in protecting host from foreign substances (bacteria)
ºInvolved in protecting host from itself (cancer)
•Extremely diverse- mount defense against virtually any invasion
•Not limited to whole organisms, can us portions of organisms
•Basis for many vaccines
ºChallenging person with portion of organism often confers protection against infection




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ºRisk free form of vaccination (no chance for disease)




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Principles of Immunity

Two broad branches of immunity:




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•Innate Immunity: non-specific response, effective against broad spectrum of immunological
challenges
•Adaptive Immunity: highly tailored and precise response against specific immunological
challenge, further divided into two branches
ºHumoral Adaptive Immunity: B cell centered, antibodies primary effector, mature in bone
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marrow
ºHumoral Cell Mediated Immunity: T cell centered, cells primary effector, mature in thymus

•Two branches intimately intertwined, components of both in any immune response
•Same true for subdivisions of adaptive immunity, all immune responses have aspects of
humoral and cell mediated adaptive immunity
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ADCC: Antibody-Dependent Cell Mediate Cytocity
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Principles of Innate Immunity
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Cells involved lack pathogen specific receptors, effective against many pathogens

•Phagocyte: cells capable of undergoing phagocytosis, include polymorphic neutrophils (PMN),
macrophages (MΦ), dendritic cells (DC), and eosinophils

ºPMN, MΦ, and eosinophils contribute to clearance of pathogens

ºDC do not significantly contribute to clearance of pathogens, professional Antigen Presenting
Cell (pAPC), present antigens to T(H) cells to promote activation

,•Other cells involved in other aspects of innate immunity include mast cells (inflammation),
natural killer cells (NK cells, exert cytotoxicity for problematic cells), and basophils
(inflammation)

Each cell type confers different aspect to innate immunity




Principles of Adaptive Immunity




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•Adaptive immune response exhibits exquisite specificity- directed to unique challenge
•Cell mediated immunity involves two classes of T cells, both have membrane bound antigen
specific receptor- T Cell Receptor (TCR), antigen binding activates both classes




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ºT(H): Helper T cells, involved in activation of CMI, recognize antigens presented by MHC Class
II molecules (pAPC's)
ºT(C): Cytotoxic T cells, involved in killing of problematic cells, recognize antigens presented by




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MHC Class I molecules (target cells)
•Humoral immunity also relies on membrane bound antigen specific receptor, B Cell Receptor
(BCR), membrane bound immunoglobulin (antibody)
ºBCR on resting B cell binds to specific antigen, facilitates activation
ºActivated B cell proliferates and differentiates into Plasma Cell- effector cell, produces soluble
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antibodies, effector for humoral immunity


Organs Required for Immunity

Two broad classes of lymphoid tissue required for immunity
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•Primary Lymphoid Tissue: site of maturation and acquisition of immunocompetent
ºBone Marrow: site of maturation of B cells and most other blood cells (RBC, mast cells,
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platelets, eosinophils, basophils, MΦ, PMN, DC)
ºThymus: site of maturation of all T cells (T(C), T(H)), NK cells, and DC
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•Secondary Lymphoid Tissue: site of activation and differentiation of immune cells
ºLymph Modes: site of activation for tissue derived antigens
ºSpleen: site of activation for circulation derived antigens
ºMuscosal Associated Lymphoid Tissue (MALT): site of activation of mucous membrane-derived
antigens


Where do Leukocytes come from?

•All blood cells created hematopoiesis (pleuripotent)
•Involves differentiation of Hematopoietic Stem Cells (HSC)

, ºCapable of differentiating into all types of blood cells
ºSelf renewing- maintain population by cell division
•Begins embryonic yolk sac for mammals
•Initially HSCs differentiate exclusively into red blood cells (RBC)
•In third mouth HSCs migrate to spleen and liver
•In seventh primarily develop in bone marrow

•Single cell HSC progenitor generates all cells required, gives rise to two progenitor cell types
•Lymphoid Progenitor Cell: gives rise to T cells, B cells, dendritic cells, and natural killer cells
(NK or Innate Lymphoid Cell (ILC))




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•Myeloid Progenitor Cell: gives rise to macrophages, neutrophils, eosinophils, basophils, mast
cells, RBC, and platelets, and dendritic cells
•Differentiation to any progenitor type is committal step




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ºCan no longer differentiate to any cell type
ºNo longer have capacity for self renewal




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How do Stem Cells know what to do?
•HSCs have many possible fates, need instructions

•Receives instructions through small signaling molecule- Cytokines
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•Small polypeptide (protein) molecules- over 120 different cytokines

•Each activates transcription of different subset of genes

•Type of cytokine that stimulates HSC to proliferate dictates fates
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•Differentiation occurs on network of bone marrow and thymus Stromal Cells
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•Generates Hematopoietic-Inducing Microenvironment: matrix and cells with bound or diffusible
growth factors (cytokines)
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The Innate Immune Response

Innate immune system has 5 components
•Anatomic (physical) barriers
•Physiological barriers
•Phagocytic/endocytic barriers
•Inflammatory barriers
•Antimicrobial substances