Ch. 11, Immunology Basics - Microbiology

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Disease

Tumor

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Definition:Definition:

Is the science dealing with the study of processes by which the body defends and maintains the constancy of self structures against invasion by foreign agents or development of unwanted cells or cell products within itself.

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Definition:Definition:The state of rapid and higher responsiveness in a trial for :Elimination of an antigen previously detected by the immune system and formation of memory lymphocyte cells.

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Cosists of organs, cells and molecules responsiblefor recognition and elimination of unwanted agents.

Organs:Organs: as thymus gland and lymph nods.

Cells:Cells: as macrophages and lymphocytes.

Molecules:Molecules: as immunoglobulins.

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Factors played by the microbe.Factors played by the microbe.

Factors played by the host.Factors played by the host.

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Is the biological processes which takes place in the host as a result of penetration, colonization and multiplication of pathogenic microorganism into it, independant whether the penetration will lead to development of an obvious disease or latent disease, or the host will only become a carrier of the pathogenic microorganism.

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I. Natural Resistance (Non-specific immune mechanism or Natural or Innate Immunity).

II. Acquired Immunity ( Specific immune mechanism).

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Difference between specific and non-specific Immunity

Non-specific Imm.Specific Immunity

Its response is Ag independent.Its response is Ag dependent.

Immediate maximal response.Lag time before response.

Not Ag. Specific.It is Ag. Specific.

No immunological memory.Immunological memory.

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OrgansOrgans

CellsCells

MoleculesMolecules

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Major Lymphoid Organs & TissuesMajor Lymphoid Organs & TissuesMajor Lymphoid Organs & TissuesMajor Lymphoid Organs & Tissues

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ORGANS I. Central Lymphoid Organs (Primary):

* Bone marrow.* Thymus gland.

II. Peripheral Lymphoid Organs (Secondary):

* Lymph nodes.* Spleen.* Tonsils.* Mucosa associated lymphoid tissues.

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Thymus SectionThymus SectionThymus SectionThymus Section

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Spleen SectionSpleen SectionSpleen SectionSpleen Section

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Lymph nodeLymph nodeLymph nodeLymph node

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Defintion: Summation of all natural defence mechanisms.

Determining Factors: 1- Genetic factor. 2- Age. 3- Nutritional and metabolic factors. 4- Hormonal Factor.Mechanisms: 1- Mechanical defence.2- Bacterial Flora.3- Inflammatory response4- Fever.5- Biochemical tissue constituents (Humoral).6- Phagocytosis.

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Factors that control innate immunityFactors that control innate immunityFactors that control innate immunityFactors that control innate immunity

Genetic Factor: Species and strain: The rat is unsusceptible to

diphtheria while the guinea pig and man are susceptible.

Races: Negroes are more susceptible to T.B. than white races.

Individual: Some individuals in the same family are more susceptible to infections.

Genetic Factor: Species and strain: The rat is unsusceptible to

diphtheria while the guinea pig and man are susceptible.

Races: Negroes are more susceptible to T.B. than white races.

Individual: Some individuals in the same family are more susceptible to infections.

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Age Factor:Extremes are more susceptible to infection.

Nutritional and Metabolic Factors: Inadequate diet increasing Susceptibility to

infection .

Hormonal Factors: Diabetes mellitus, hypothyoidism and Adrenal dysfunction, increases the susceptibility to infection.

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1-Mechanical Barriers1-Mechanical Barriers1-Mechanical Barriers1-Mechanical Barriers

SkinSkin Mucous membraneMucous membrane

Hair & CiliaHair & CiliaWashingWashing

PeristalsisPeristalsis

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2-Normal 2-Normal Bacterial FloraBacterial Flora

2-Normal 2-Normal Bacterial FloraBacterial Flora

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It is necessary to direct elements of immune system to site of infection by three things: 1) Increase blood supply to infected area--> Redness. 2) Increase capillary permeability---> Oedema. 3) Neutophils & Macrophages migrate out of capillaries into the surrounding tissues, and by the effect of chemotactic factors ( C5a) migrate towards the site of infection ( Chemotaxis).

33--InflammationInflammation 33--InflammationInflammation

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InflammationInflammation InflammationInflammation

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InflammationInflammation

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4-Fever4-Fever4-Fever4-Fever The most common symptome of infection (Except few cases as syphilis).

Imporance in host defence: - Human lymphocytes in vivo at 39 C show higher uptake of thymidine than at 37 C. - Human leucocytes show maximum phagocytic activity between 38-40 C. - Circulating iron decrease during fever & reduce microbial iron.

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Mechanism: Affection of thermoregulatory center in hypothalamus by different substances as: endotoxins of Gram-negative bacteria (Exogenous pyrogen) and extract from macrophages called interleukin-1 (Endogenous pyrogen).

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5-Biochemical Tissue Constituents5-Biochemical Tissue Constituents5-Biochemical Tissue Constituents5-Biochemical Tissue Constituents* Stomach acidity.* Lysozyme.* Serum betalysin.* Acute phase protein.* Properdin.* Lactoperoxidase.* Lactoferrin.* Interferon.* Complement.* Interferone.

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Natural Defence BarriersNatural Defence BarriersNatural Defence BarriersNatural Defence Barriers

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DefinitionDefinitionDefinitionDefinitionCapture and digestion of particulate foreign materials byphagocytic cells.

Types of Phagocytic Cells

1- Polymorphnuclear leucocytes (Neutrophils or Microphages): * First line of defense. * 60 % of cells. * Contains two types of granules: lyzosome & phagocytin.

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2- Mononuclear phagocytes (Macrophages) (R.E.S.): * Second line of defense. * Found as: - Wandering (in circulation). - Fixed in ( tissues). * Functions: - Secretory: lysozyme, IL1, Monokines, T.N.F. Interferon (), complement components. - Antigen-presenting cell (recognition, processing and presentation in suitable dose for other lymphocytes). - Phagocytosis.

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3- Eosinophils: phagocytic & cytotoxic for larger parasites as worms. Also regulate the inflammatory response.

4- Basophils: contains heparin and vasoactive amines imprtant for inflammatory response.

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Mechanism of PhagocytosisMechanism of Phagocytosis

Chemotaxis

AdherenceNon-Specific Binding

Specific Opsonization)

Ingestion

DigestionOxygen-dependent system (Respiratory burst)

Oxygen-independent agents

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PhagocytosisPhagocytosis

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OpsonizationOpsonization