DISEASES OF IMMUNITY

Dr.Ayesha Ahmed

IMMUNITYIMMUNITYResistance of an organism to infection .Resistance of an organism to infection .

Immune system is the collection of cells and Immune system is the collection of cells and molecules responsible for defending against the molecules responsible for defending against the pathogenic organism.pathogenic organism.

INNATE:INNATE: NATURAL, Native . First line of defenseNATURAL, Native . First line of defense

AQUIREDAQUIRED : Developed by exposure to pathogens, : Developed by exposure to pathogens, antigens. Second line of defenseantigens. Second line of defense

INNATE IMMUNITYINNATE IMMUNITY

BARRIERS: BARRIERS: Epithelial barriers of skin, GIT and respiratory Epithelial barriers of skin, GIT and respiratory tract. Tears, salivatract. Tears, saliva

CELLS:CELLS: Neutrophils, macrophages, Natural killer cells . Neutrophils, macrophages, Natural killer cells .

PLASMAPLASMA PROTEINSPROTEINS: Complement system .: Complement system .

ACQUIRED IMMUNITYACQUIRED IMMUNITYHUMORAL IMMUNE RESPONSES: HUMORAL IMMUNE RESPONSES: Involve the activation of Involve the activation of BB cells cells which produce antibodies.which produce antibodies.AntibodiesAntibodies provide protection against provide protection against extracellular microbes in the blood, extracellular microbes in the blood, mucosal secretions and tissues.mucosal secretions and tissues.

CELL MEDIATED IMMUNE CELL MEDIATED IMMUNE RESPONSESRESPONSES: : Involves the Involves the activation of activation of T T cellscells which identify which identify and destroy the infected cells.and destroy the infected cells.Defense against intracellular Defense against intracellular organism.organism.

HELPER T CELLSHELPER T CELLS:: Aid both Aid both responsesresponsesCYTOTOXIC T CELLS:CYTOTOXIC T CELLS: Destroy the Destroy the infected body cellsinfected body cells

A A primary immuneprimary immune response occurs when the response occurs when the body is first exposed to an antigen .body is first exposed to an antigen .

A A secondary immunesecondary immune response occurs when the response occurs when the same antigen is encountered at later time. It is same antigen is encountered at later time. It is faster and of greater magnitude.faster and of greater magnitude.

CELLS OF THE IMMUNE SYSTEMCELLS OF THE IMMUNE SYSTEM

T LYMPHOCYTEST LYMPHOCYTESB LYMPHOCYTESB LYMPHOCYTES

PLASMA CELLS PLASMA CELLS (MODIFIED B CELLS)(MODIFIED B CELLS)CYTOTOXIC T CELLSCYTOTOXIC T CELLS

ANTIGEN PRESENTING CELLS ANTIGEN PRESENTING CELLS Macrophages, Macrophages, Dendritic cellsDendritic cells

NORMAL IMMUNE RESPONSENORMAL IMMUNE RESPONSE

APCsAPCs Macrophages, Macrophages, Dendritic Cells)Dendritic Cells)

CD4CD4 HelperHelper

CD8CD8 Effector Effector

B-CellsB-Cells Plasma Cells Plasma Cells Antibodies( IgA, D, E, M, G)Antibodies( IgA, D, E, M, G)

IMMUNE SYSTEM DISORDERSIMMUNE SYSTEM DISORDERS

HYPERSENSITIVITY REACTIONSHYPERSENSITIVITY REACTIONS

AUTO IMMUNE DISEASES AUTO IMMUNE DISEASES

IMMUNO DEFICIENCY SYNDROMES IMMUNO DEFICIENCY SYNDROMES

DISORDERS OF THE DISORDERS OF THE IMMUNE SYSTEMIMMUNE SYSTEM

HypersensitivityHypersensitivity• Too muchToo much

ImmunodeficiencyImmunodeficiency• Too littleToo little

AutoimmunityAutoimmunity• MisdirectedMisdirected

AUTO-IMMUNITYAUTO-IMMUNITY

Immunological Tolerance: Immunological Tolerance: Unresponsiveness to self Unresponsiveness to self antigens .antigens .

Failure of Self Tolerance leads to Failure of Self Tolerance leads to Auto immune diseasesAuto immune diseases

Strong genetic PredispositionStrong genetic Predisposition

Often triggered by InfectionsOften triggered by Infections

AUTOIMMUNE DISEASESAUTOIMMUNE DISEASES

A Group of 60 to 80 chronic inflammatory A Group of 60 to 80 chronic inflammatory diseases with genetic predisposition and diseases with genetic predisposition and environmental modulationenvironmental modulation

Prevalence is greater for females than malesPrevalence is greater for females than males

CLASSIFICATION OF AUTOIMMUNE CLASSIFICATION OF AUTOIMMUNE DISEASESDISEASES

Organ SpecificOrgan Specific• Insulin dependent diabetes mellitus (IDDM) - Type IInsulin dependent diabetes mellitus (IDDM) - Type I• Graves’ diseaseGraves’ disease

SystemicSystemic• Systemic lupus erythematosusSystemic lupus erythematosus• Rheumatoid arthritisRheumatoid arthritis

RISK FACTORS FOR RISK FACTORS FOR AUTOIMMUNE DISEASESAUTOIMMUNE DISEASES

GeneticGenetic

FemaleFemale

EnvironmentalEnvironmental

DrugsDrugs

InfectionsInfections

CLASSIC AUTOIMMUNE DISEASESCLASSIC AUTOIMMUNE DISEASES

Systemic Lupus Systemic Lupus ErythematosusErythematosus

Rheumatoid ArthritisRheumatoid Arthritis

SYSTEMIC LUPUS SYSTEMIC LUPUS ERYTHEMATOSUS (SLE)ERYTHEMATOSUS (SLE)

Chronic, multi-system inflammatory disease with Chronic, multi-system inflammatory disease with protean manifestations and remitting courseprotean manifestations and remitting course

Clinical manifestationsClinical manifestations– Musculoskeletal (joint and muscle pain)Musculoskeletal (joint and muscle pain)– Dermatological (malar rash)Dermatological (malar rash)– Renal (glomerulonephritis)Renal (glomerulonephritis)

Female to male ratio of 9:1Female to male ratio of 9:1

Etiology is unknownEtiology is unknown

RHEUMATOID ARTHRITIS (RA)RHEUMATOID ARTHRITIS (RA)

Characterized by inflammation of synovial membrane of Characterized by inflammation of synovial membrane of joints and articular surfaces of cartilage and bonejoints and articular surfaces of cartilage and bone

Female to male ratio of 3:1Female to male ratio of 3:1

IMMUNODEFICIENCIEIMMUNODEFICIENCIESS

Due to impaired function of Due to impaired function of one or more components of one or more components of the immune or inflammatory the immune or inflammatory responses. responses. Problem may be with:Problem may be with:

– B cellsB cells– T cellsT cells– PhagocytesPhagocytes– Complement Complement

componentscomponents

Hallmark: Tendency to develop unusual or recurrent,severe infections.

Deficiencies in T / B cells may lead to recurrent infections by certain bacteria, viruses or fungi .

AIDSAIDSAcquired Immuno Defficiency Acquired Immuno Defficiency

SyndromeSyndrome

EtiologyEtiology:: HIV(HIV(Human immunodeficiency virus)Human immunodeficiency virus)

TransmissionTransmission:: Through direct contact of mucous Through direct contact of mucous membrane or blood stream with a bodily fluid containing membrane or blood stream with a bodily fluid containing HIV, such as blood.HIV, such as blood.Transplacental (mother to child)Transplacental (mother to child)

PathogenesisPathogenesis:: HIV causes AIDS by depleting CD4+ helper T HIV causes AIDS by depleting CD4+ helper T cells.cells.Weakening of Immune System and this Weakening of Immune System and this allows opportunistic infections.allows opportunistic infections.

Clinical FeaturesClinical Features: : Oppurtunistic InfectionsOppurtunistic Infections Conditions that do not normally develop in Conditions that do not normally develop in individuals with healthy immune system.individuals with healthy immune system.Caused by bacteria, viruses, fungi and Caused by bacteria, viruses, fungi and parasitesparasitesHigh incidence of certain tumorsHigh incidence of certain tumors

HYPERSENSTIVITY

Hypersensitivity ReactionHypersensitivity Reaction

Hypersensitivity Hypersensitivity * An immune response resulting in exaggerated reactions * An immune response resulting in exaggerated reactions

harmful to the hostharmful to the host

* There are * There are four typesfour types of hypersensitivity reactions: of hypersensitivity reactions:

Type I, Type II, Type III, Type IV Type I, Type II, Type III, Type IV

* Types I, II and III are * Types I, II and III are antibody mediatedantibody mediated

* Type IV is * Type IV is cell mediatedcell mediated

Hypersenstivity ReactionHypersenstivity Reaction

I (Immediate Hypersensitivity)I (Immediate Hypersensitivity)

II (Antibody Mediated Hypersensitivity)II (Antibody Mediated Hypersensitivity)

III (Immune-Complex Mediated Hypersensitivity)III (Immune-Complex Mediated Hypersensitivity)

IV (Cell-Mediated Hypersensitivity)IV (Cell-Mediated Hypersensitivity)

FOUR Hypersenstivity ReactionsFOUR Hypersenstivity Reactions..

Type Alternate name Often Mentioned disorders Mediators

IAllergic , Immediate

Asthma IgE

IIAntibody mediated

Auto Immune hemolytic Anemia

IgM, IgGComplement

IIIImmune complex mediated

Systemic Lupus Ereythmatosus

IgGComplement

IV Cell mediatedTuberculosisTuberculin Test

T cell

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