The Immune System

• OverviewOverview– Systems involvedSystems involved– Cells involvedCells involved

• Non-specific ImmunityNon-specific Immunity• Specific ImmunitySpecific Immunity

– AntibodiesAntibodies– ComplementComplement– Immunology TutorialImmunology Tutorial

Host defense mechanisms

First line of defenseFirst line of defense: host ____________ and : host ____________ and chemical barriers (skin, mucous, tears, etc.)chemical barriers (skin, mucous, tears, etc.)

Second line of defenseSecond line of defense: phagocytes and : phagocytes and

______________________ (non-specific)______________________ (non-specific)

Third line of defenseThird line of defense: __________________ : __________________ immune reactionsimmune reactions

Systems involved in immune defenses

1) 1) BloodstreamBloodstream

2) 2) Lymphatic systemLymphatic system

3) 3) Reticuloendothelial (or mononuclear Reticuloendothelial (or mononuclear phagocyte) systemphagocyte) system -- support system of -- support system of _____________________ tissue fibers and _____________________ tissue fibers and endotheliumendothelium

4) 4) Extracellular fluidExtracellular fluid

Communicating systems

Communicating systems

Important blood cells involved in immune systems

Stem cellsStem cells -- undifferentiated cells which give rise to all the -- undifferentiated cells which give rise to all the others. Found in __________ ____________. Produce others. Found in __________ ____________. Produce erythrocytes (RBCs), erythrocytes (RBCs), leukocytesleukocytes (WBCs), and platelets (WBCs), and platelets

LeukocytesLeukocytes are generally divided into 2 groups: are generally divided into 2 groups: granulocytesgranulocytes (polymorphonuclear __________________) (polymorphonuclear __________________) and and agranulocytes agranulocytes (mononuclear leukocytes)(mononuclear leukocytes)Examples of granulocytesExamples of granulocytes: neutrophils (“microphage”), basophils, : neutrophils (“microphage”), basophils,

eosinophilseosinophils

Examples of agranulocytesExamples of agranulocytes: monocytes, lymphocytes: monocytes, lymphocytes

Granular leukocytesGranular leukocytes

ErythrocytesErythrocytes

Agranular leukocyteAgranular leukocyte

AgranulocytesLymphocytesLymphocytes

__________________________ -- derived from the thymus. -- derived from the thymus. Important in Important in cell-mediated immunitycell-mediated immunity..

__________________________ -- derived from bone marrow, -- derived from bone marrow, primarily. primarily. Important in Important in humoral immunityhumoral immunity..

Monocytes -- large, common, important in Monocytes -- large, common, important in ____________________ and specific immune ____________________ and specific immune functions. Non-circulatory (tissue-associated) functions. Non-circulatory (tissue-associated) monocytes are known as monocytes are known as macrophagesmacrophages. .

LymphocyteLymphocyte: note_____________ nucleus, little cytoplasm.: note_____________ nucleus, little cytoplasm. Is smaller than monocyteIs smaller than monocyte

NeutrophiNeutrophil l (a granular (a granular leukocyte): note leukocyte): note

granules and granules and ___________ nucleus___________ nucleus

MonocyteMonocyte: note unlobed, : note unlobed,

rounded nucleus and rounded nucleus and

apparent lack of granulesapparent lack of granules

Non-Specific Immune Reactions

• InflammationInflammation

• Phagocytosis (and presentation)Phagocytosis (and presentation)

• ComplementComplement

““Rubor” -- __________Rubor” -- __________““Calor” -- warmthCalor” -- warmth““Tumor” -- ____________Tumor” -- ____________““Dolor” -- painDolor” -- pain

Non-specific Immunity: Phagocytosis

• Carried out primarily by neutrophils and by Carried out primarily by neutrophils and by monocytes/macrophages (collectively called monocytes/macrophages (collectively called ‘_______________’)‘_______________’)

The scanning electron micrograph above, shows a human macrophage (gray) approaching a Streptococcus pyogenes (yellow). Riding atop the macrophage is a spherical lymphocyte. Both macrophages and lymphocytes can be found near an infection, and the interaction between these cells is important in eliminating infection.

Phagocytosis by Macrophages

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Phagocytic killing

Phagocytes Phagocytes shift from aerobic to shift from aerobic to

______________________________________ metabolism. Leads metabolism. Leads

to to drop in _________drop in _________, which activates , which activates

lysosomal enzymes.lysosomal enzymes.

Oxygen-dependent phagocytic killing

Phagocyte failure

Pathogens can neutralize phagocyte products:Pathogens can neutralize phagocyte products: __________________________________________ produces carotenoids produces carotenoids

which quench singlet oxygenwhich quench singlet oxygen Mycobacterium sp.Mycobacterium sp. can grow can grow withinwithin

macrophages using glycolipids in their cells macrophages using glycolipids in their cells walls to scavenge toxic _________________ walls to scavenge toxic _________________ speciesspecies

Strep. pyogenesStrep. pyogenes and and Staph. aureusStaph. aureus produce produce leukocidinsleukocidins which destroy ________________. which destroy ________________.

Specific Immunity: Antibodies or Immunoglobulins

IgGIgG

The complement system““Complement” is an additional mechanism that is brought into play at Complement” is an additional mechanism that is brought into play at

several levels in _______ __________.several levels in _______ __________.Is a Is a cascadecascade of proteins which result in membrane permeation and cell death of proteins which result in membrane permeation and cell death

The Complement System: a Summary

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