CHPT 7-Immunity canvas ppt

Immune System

• Responsible for body defenses.

  • Nonspecific response (defense).

    • Examples: phagocytosis, inflammation.

  • Specific response (defense).

    • Production of specific antibodies against foreign substances.

Components of the Immune System

• Lymphoid structures.

  • Lymph nodes.

  • Spleen.

  • Tonsils.

  • Intestinal lymphoid tissue.

  • Lymphatic circulation.

• Immune cells.

  • Lymphocytes.

  • Macrophages.

• Tissues—immune cell development

  • Bone marrow

    • Origination of all immune cells

  • Thymus

    • Maturation of T lymphocytes

• Chemical mediators

  • Histamine, interleukins

Elements of the Immune System

• Antigens / Cells/ Complement System / Chemical Mediators

  • Antigens

    • Self

      • MHC is referred to as HLA (Human Leukocyte Antigen) proteins label cells of the individual.

      • Immune system ignores self-cells.

    • Non-self

      • Immune system recognizes specific nonself antigens as foreign.

      • Development of a specific response to that particular antigen

      • Memory cells produced to respond quickly to antigen

  • Usually exogenous substances

    • Cell surface antigens

      • Proteins

      • Polysaccharides

      • Glycoproteins

Cells

• Macrophages (non specific)

  • Initiation of immune response

  • Develop from monocytes

  • Part of the mononuclear phagocytotic system

  • Engulf foreign material

  • Display antigens of foreign material

  • Secrete chemicals

    • Examples: monokines, interleukins

  • Present throughout the body

• Lymphocytes ( one of the White Blood Cells)

  • There are 2 groups T and B Lymphocytes

    • T lymphocytes- Kills Directly

      • From bone marrow stem cells

      • Further differentiation in thymus

      • Cell-mediated immunity

      • Cytotoxic T killer cells

      • Helper T cells

      • Memory T cells

    • B lymphocytes- produce antibodies to kill

      • Responsible for production of antibodies

      • Humoral immunity

      • Mature in bone marrow

      • Proceed to spleen and lymphoid tissue

      • Plasma cells

        • Produce antibodies

      • B memory cells

        • Can quickly form clone of plasma cells

Types of Immunity

• Humoral immunity: Antibodies are produced to protect the body. ( B cells)

• Cell-mediated immunity (CMI): Lymphocytes are programmed to attack nonself cells to protect the body. ( T Cells)

Antibodies and Immunoglobulins

• IgG

  • Most common in blood comes from mother or after initial exposure ( IgM) – memory cells

• IgM

  • First to increase in immune response – Initial exposure

• IgA

  • In secretions

    • Tears

    • Saliva and mucous membranes

    • Colostrum

• IgE

  • Allergic response

  • Causes release of histamine and other chemicals

  • Results in inflammation

• IgD

  • Attached to B cells

  • Activates B cells

Complement System

• Activated during immune reactions with IgG or IgM

• Group of inactive proteins circulating in blood

• C1 to C9

• Causes cell damage and further inflammation when activated

Chemical Mediators

• Involved in inflammation and immune reactions

  • Examples: histamine, cytokines

• Variety of functions

  • Signaling

  • Causing cellular damage- can be self or pathogen

    • Self: like allergies

Immune Response

• “self” antigen

  • Normally ignored by the immune system

  • Tolerance

• “nonself” antigen

  • Foreign

  • Specific response to a specific antigen

    • Stored in memory cells for future reference

Immunity

• Natural immunity

  • Species-specific – things like distemper only animals can get like dogs

• Innate immunity

  • Gene-specific

  • Related to ethnicity

• Primary response

  • First exposure to antigen

  • 1 to 2 weeks before antibody titer reaches efficacy

• Secondary response

  • Repeat exposure to the same antigen

  • More rapid response, with efficacy in 1 to 3 days

Types of Acquired Immunity

• Natural active

  • Mechanism: Pathogens enter body and cause illness; antibodies form in host

  • Memory: Yes

  • Example: Person has chickenpox once

• Artificial active

  • Mechanism: Vaccine (live or attenuated organisms) is injected into person. No illness results, but antibodies form

  • Memory: Yes

  • Example: Person has measles vaccine and gains immunity

• Natural passive

  • Mechanism: Antibodies passed directly from mother to child to provide temporary protection

  • Memory: No

  • Example: Placental passage during pregnancy or ingestion of breast milk

• Artificial passive

  • Mechanism: Antibodies injected into person (antiserum) to provide temporary protection or minimize severity of infection

  • Memory: No

  • Example: Gammaglobulin if recent exposure to microbe

Outcome of Infectious Disease

• Some occurrence has declined where vaccination rates are high.

  • Previous infections

  • “herd immunity”

  • Outbreaks (measles, mumps) in North America due to inadequate revaccination of teens

• Search for additional vaccines continuous

  • AIDS, malaria, tuberculosis and others

  • Research on genetic vaccines

Emerging, Re-emerging

• Emerging infectious diseases

  • Newly identified in a population

• Re-emerging infectious diseases

  • Previously under control

    • No consistence in vaccination programs

    • On rise due to globalization, drug resistance, and other factors

    • Example: measles in the United States

Bioterrorism

• Biological agents used to attack civilians and/or military personal

• May use altered antigenic forms of common viruses or bacteria

• Widespread impact on population due to a lack of vaccines

Tissue and Organ Transplant Rejection

• Hyperacute rejection

  • Immediately after transplantation

• Acute rejection

  • Develops after several weeks

• Chronic, late rejection

  • Occurs after months or years

Immunosuppression

• Reduction of immune response to prevent rejection

• Commonly used drugs

  • Cyclosporine, azathioprine, prednisone

• High risk of infection

  • Caused by immunosuppression

  • Opportunistic organisms

Hypersensitivity Reactions

• Type I hypersensitivity—allergic reactions (asthma/food allergy/anaphylaxis) - IgE

  • Common

    • Caused by allergen

    • Skin rashes

    • Hay fever

  • Causative mechanism

    • Exposure to allergen

    • Development of IgEs

    • Mast cells

  • Complications

    • Anaphylaxis

• Type I hypersensitivity–allergic reactions (cont.)

  • Hay fever: allergic rhinitis

    • Nasal mucosa

  • Food allergies

    • Digestive tract mucosa

  • Atopic dermatitis/eczema

    • Skin

  • Asthma

    • Bronchial mucosa

Anaphylaxis: Anaphylactic Shock

• Severe, life-threatening

• Systemic hypersensitivity reaction

• Decreased blood pressure caused by release of histamine

• Airway obstruction

• Severe hypoxia

• Can be caused by:

  • Latex materials

  • Insect stings

  • Nuts or shellfish; various drugs

• Signs and symptoms

  • Generalized itching or tingling, especially in oral cavity

  • Coughing / Difficulty breathing

  • Feeling of weakness / Dizziness or fainting

  • Sense of fear and panic

  • Edema around eyes, lips, tongue, hands, feet

  • Hives

  • Collapse with loss of consciousness

Type II: Cytotoxic Hypersensitivity

• Antigen is present on cell membrane

  • May be normal body component or exogenous

• Circulating IgGs react with antigen

  • Destruction by phagocytosis or cytolytic enzymes

• Example

  • Response to incompatible blood transfusion

  • Graft Rejection

  • Know The Types of Graft: Xenograft / Alograft / Autograft

Type III: Immune Complex Hypersensitivity

• Antigen combines with antibody

  • Forms immune complexes, deposited in tissue

  • Activation of complement system

• Process causes inflammation and tissue destruction

• Examples:

  • Glomerulonephritis

  • Rheumatoid arthritis

  • SLE

  • Serum Sickness

Type IV: Cell-Mediated or Delayed Hypersensitivity

• Delayed response by sensitized T lymphocytes

• Release of lymphokines

• Inflammatory response

• Destruction of the antigen

• Examples

  • Poison Ivy

  • Tuberculin test

  • Contact dermatitis

  • Allergic skin rash

Autoimmune Disorders

• Development of antibodies against own cells or tissues

• Autoantibodies are antibodies formed against self-antigens—loss of self-tolerance.

• Disorder can affect single organs or tissues or can be generalized.

• Examples:

  • Hashimoto thyroiditis, systemic lupus erythematosus, rheumatic fever, myasthenia gravis, scleroderma, pernicious anemia

Systemic Lupus Erythematosus (SLE)

• Type III Hypersensitivity

• Chronic inflammatory disease

• Affects a number of organ systems

• Characteristic facial rash—“butterfly rash”

• Affects primarily young women

• Incidence is higher in African Americans, Asians, Hispanics, Native Americans

• Large number of circulating autoantibodies

  • Against DNA, platelets, erythrocytes

• Formation of immune complexes

  • Deposited into tissues

• Inflammation and necrosis

• Vasculitis develops in many organs.

  • Impairs blood supply to the tissues

• Signs and symptoms vary because of organ involvement but commonly include:

  • Arthralgia, fatigue, malaise

  • Cardiovascular problems

  • Polyuria

Immunodeficiency

• Partial or total loss of one or more immune system components

• Predisposition to the development of opportunistic infections

• Increased risk of infection and cancer

• Primary deficiencies

  • Basic developmental failure somewhere in the system

• Secondary or acquired immunodeficiencies

  • Loss of the immune response from specific causes

  • Can occur at any time during the life span

    • Infections, splenectomy, malnutrition, liver disease, immunosuppressant drugs, radiation, chemotherapy (cancer)

Acquired Immunodeficiency Syndrome (AIDS)

• AIDS—chronic infectious disease caused by the human immunodeficiency virus (HIV)

• HIV destroys helper T cells—CD4 lymphocytes.

• Loss of immune response

• Increased susceptibility to secondary infections and cancer

• Prolonged latent period

• HIV-positive individual

  • Virus is known to be in the body.

  • No evidence of immunosuppression

• AIDS

  • Marked clinical symptoms, multiple complications

  • Individual often identified as HIV-positive before development of AIDS

The Agent

• Human immunodeficiency virus

• Retrovirus

  • Member of the subfamily, lentavirus

• HIV-1

  • Major cause of AIDS in US and Europe

• HIV-2

  • Major cause of AIDS in central Africa

Transmission

• Bodily fluids

  • Blood

  • Semen

  • Vaginal fluids

Clinical Signs and Symptoms

• Generalized effects

  • Lymphadenophathy

  • Fatigue and weakness

  • Headache

  • Arthralgia

  • Gastrointestinal effects primarily due to opportunistic infections

• Encephalopathy

  • Sometimes called AIDS dementia

    • Direct infection of brain cells by HIV

Secondary Infections

• Primary cause of death

• Frequently multiple, more extensive and severe than usual

• Lungs

  • Pneumocystis carinii

• Herpes simplex

  • Cold sores

• Candida

  • Involves mouth and often esophagus

• Tuberculosis

Cancer and AIDS

• Increased incidence of all cancers

• Unusual cancers are often markers for AIDS.

  • Kaposi sarcoma

    • Affects the skin, mucous membranes, and internal organs

  • Non-Hodgkin lymphoma

    • Purple or brown nonpruritic, painless patches

    • Eventually become nodular

• Responsible for body defenses.

• Nonspecific response (defense):

  • This is the initial, rapid response to any foreign invader, regardless of its identity.

  • Examples:

  • Phagocytosis: Engulfing and destroying pathogens or debris by cells like macrophages and neutrophils.

  • Inflammation: A localized physical condition of redness, swelling, heat, and pain due to tissue damage or infection.

• Specific response (defense):

  • This is a slower but more targeted response that involves the production of specific antibodies against foreign substances (antigens).

  • Key features:

  • Specificity: The immune response is tailored to the specific antigen encountered.

  • Memory: The immune system remembers previous encounters with antigens and can mount a faster and more effective response upon re-exposure.

Components of the Immune System

• Lymphoid structures:

  • These are the organs and tissues where immune cells develop, mature, and carry out their functions.

  • Lymph nodes:

  • Small, bean-shaped structures located along lymphatic vessels.

  • Filter lymph and contain lymphocytes and macrophages, which trap and destroy pathogens.

  • Spleen:

  • Located in the upper left abdomen.

  • Filters blood, removes damaged blood cells, and contains lymphocytes and macrophages that respond to bloodborne pathogens.

  • Tonsils:

  • Located in the throat.

  • Trap pathogens entering the body through the nose or mouth.

  • Intestinal lymphoid tissue (Peyer's patches):

  • Located in the lining of the small intestine.

  • Monitor the gut for pathogens and initiate immune responses.

  • Lymphatic circulation:

  • A network of vessels that collect and transport lymph, a fluid containing immune cells and antigens, throughout the body.

• Immune cells:

  • These are the cells that carry out the immune response. Examples include:

  • Lymphocytes:

  • A type of white blood cell that includes T cells, B cells, and natural killer (NK) cells.

  • T cells and B cells are responsible for specific immunity, while NK cells are part of the innate immune system.

  • Macrophages:

  • Phagocytic cells that engulf and destroy pathogens, cellular debris, and foreign substances.

  • Also present antigens to T cells, initiating the adaptive immune response.

• Tissues—immune cell development:

  • Bone marrow:

  • The soft, spongy tissue inside bones.

  • Site of origin of all immune cells.

  • Thymus:

  • Located in the chest.

  • Site of maturation of T lymphocytes (T cells).

• Chemical mediators:

  • These are molecules that regulate the immune response. Examples include:

  • Histamine: A chemical released by mast cells during allergic reactions, causing inflammation and vasodilation.

  • Interleukins: A group of cytokines (signaling molecules) that regulate the growth, differentiation, and activation of immune cells.

Elements of the Immune System

• Antigens / Cells / Complement System / Chemical Mediators

• Antigens:

  • Substances that can trigger an immune response.

  • Self:

  • Molecules on the surface of an individual's cells that the immune system recognizes as "self".

  • MHC (major histocompatibility complex) is referred to as HLA (Human Leukocyte Antigen) proteins label cells of the individual.

  • Immune system ignores self-cells (self-tolerance).

  • Non-self:

  • Molecules on the surface of foreign cells, such as bacteria, viruses, fungi, and parasites, that the immune system recognizes as "foreign".

  • Immune system recognizes specific nonself antigens as foreign.

  • Development of a specific response to that particular antigen.

  • Memory cells produced to respond quickly to antigen.

  • Usually exogenous substances:

  • Cell surface antigens:

    • Proteins

    • Polysaccharides

    • Glycoproteins

Cells

• Macrophages (non-specific):

  • Initiation of immune response

  • Develop from monocytes

  • Part of the mononuclear phagocytotic system

  • Engulf foreign material

  • Display antigens of foreign material

  • Secrete chemicals:

  • Examples: monokines, interleukins

  • Present throughout the body

• Lymphocytes (one of the White Blood Cells):

  • There are 2 groups T and B Lymphocytes

  • T lymphocytes:

  • From bone marrow stem cells

  • Further differentiation in thymus

  • Cell-mediated immunity

  • Types:

    • Cytotoxic T killer cells: Directly kill infected cells or tumor cells.

    • Helper T cells: Secrete cytokines that activate other immune cells, including B cells and cytotoxic T cells (CD4+)

    • Memory T cells: Provide long-lasting immunity by remembering previous encounters with antigens.

  • B lymphocytes:

  • Responsible for production of antibodies

  • Humoral immunity

  • Mature in bone marrow

  • Proceed to spleen and lymphoid tissue

  • Plasma cells:

    • Produce antibodies

  • B memory cells:

    • Can quickly form clone of plasma cells

Types of Immunity

• Humoral immunity: Antibodies are produced to protect the body. (B cells)

• Cell-mediated immunity (CMI): Lymphocytes are programmed to attack nonself cells to protect the body. (T Cells)

Antibodies and Immunoglobulins

• IgG: Most common in blood, provides long-term immunity, can cross the placenta to protect the fetus; produced after initial exposure (IgM) – memory cells

• IgM: First to increase in immune response, indicates acute infection – Initial exposure

• IgA: Found in secretions, provides localized protection on mucous membranes in:

  • Tears

  • Saliva and mucous membranes

  • Colostrum

• IgE: Involved in allergic response, binds to mast cells and basophils

  • Causes release of histamine and other chemicals

  • Results in inflammation

• IgD: Attached to B cells, serves as a receptor

  • Activates B cells

Complement System

• Activated during immune reactions with IgG or IgM

• Group of inactive proteins circulating in blood (C1 to C9)

• Activation triggers a cascade of events that lead to:

  • Opsonization: Enhancing phagocytosis of antigens

  • Chemotaxis: Attracting immune cells to the site of infection

  • Cell lysis: Directly killing pathogens by disrupting their cell membranes

• Causes cell damage and further inflammation when activated

Chemical Mediators

• Involved in inflammation and immune reactions

  • Examples: histamine, cytokines

• Variety of functions:

  • Signaling

  • Causing cellular damage: can be self or pathogen

  • Self: like allergies

Immune Response

• "self" antigen: Normally ignored by the immune system (tolerance)

• "nonself" antigen: Foreign

  • Specific response to a specific antigen

  • Stored in memory cells for future reference

Immunity

• Natural immunity: Species-specific – things like distemper only animals can get like dogs

• Innate immunity: Gene-specific, related to ethnicity

• Primary response: First exposure to antigen, takes 1 to 2 weeks before antibody titer reaches efficacy

• Secondary response: Repeat exposure to the same antigen, more rapid response, with efficacy in 1 to 3 days

Types of Acquired Immunity

• Natural active:

  • Mechanism: Pathogens enter body and cause illness; antibodies form in host

  • Memory: Yes

  • Example: Person has chickenpox once

• Artificial active:

  • Mechanism: Vaccine (live or attenuated organisms) is injected into person. No illness results, but antibodies form

  • Memory: Yes

  • Example: Person has measles vaccine and gains immunity

• Natural passive:

  • Mechanism: Antibodies passed directly from mother to child to provide temporary protection

  • Memory: No

  • Example: Placental passage during pregnancy or ingestion of breast milk

• Artificial passive:

  • Mechanism: Antibodies injected into person (antiserum) to provide temporary protection or minimize severity of infection

  • Memory: No

  • Example: Gammaglobulin if recent exposure to microbe

Outcome of Infectious Disease

• Some occurrence has declined where vaccination rates are high

  • Previous infections

  • “herd immunity”

  • Outbreaks (measles, mumps) in North America due to inadequate revaccination of teens

• Search for additional vaccines continuous

  • AIDS, malaria, tuberculosis and others

  • Research on genetic vaccines

Emerging, Re-emerging

• Emerging infectious diseases: Newly identified in a population

• Re-emerging infectious diseases: Previously under control

  • No consistence in vaccination programs

  • On rise due to globalization, drug resistance, and other factors

  • Example: measles in the United States

Bioterrorism

• Biological agents used to attack civilians and/or military personal

• May use altered antigenic forms of common viruses or bacteria

• Widespread impact on population due to a lack of vaccines

Tissue and Organ Transplant Rejection

• Hyperacute rejection: Immediately after transplantation

• Acute rejection: Develops after several weeks

• Chronic, late rejection: Occurs after months or years

Immunosuppression

• Reduction of immune response to prevent rejection

• Commonly used drugs: Cyclosporine, azathioprine, prednisone

• High risk of infection caused by immunosuppression due to opportunistic organisms

Hypersensitivity Reactions

• Type I hypersensitivity—allergic reactions (asthma/food allergy/anaphylaxis)

  • IgE-mediated

  • Common

  • Caused by allergen

  • Skin rashes

  • Hay fever

  • Causative mechanism

  • Exposure to allergen

  • Development of IgEs

  • Mast cells

  • Complications

  • Anaphylaxis

• Type I hypersensitivity–allergic reactions (cont.)

  • Hay fever: allergic rhinitis, affects nasal mucosa

  • Food allergies: affects digestive tract mucosa

  • Atopic dermatitis/eczema: affects skin

  • Asthma: affects bronchial mucosa

Anaphylaxis: Anaphylactic Shock

• Severe, life-threatening systemic hypersensitivity reaction

• Decreased blood pressure caused by release of histamine

• Airway obstruction and severe hypoxia

• Can be caused by:

  • Latex materials

  • Insect stings

  • Nuts or shellfish; various drugs

• Signs and symptoms:

  • Generalized itching or tingling, especially in oral cavity

  • Coughing / Difficulty breathing

  • Feeling of weakness / Dizziness or fainting

  • Sense of fear and panic

  • Edema around eyes, lips, tongue, hands, feet

  • Hives

  • Collapse with loss of consciousness

Type II: Cytotoxic Hypersensitivity

• Antigen is present on cell membrane

  • May be normal body component or exogenous

• Circulating IgGs react with antigen

  • Destruction by phagocytosis or cytolytic enzymes

• Example

  • Response to incompatible blood transfusion

  • Graft Rejection

  • Know The Types of Graft: Xenograft / Allograft / Autograft

Type III: Immune Complex Hypersensitivity

• Antigen combines with antibody, forming immune complexes, deposited in tissue

  • Activation of complement system

• Process causes inflammation and tissue destruction

• Examples:

  • Glomerulonephritis

  • Rheumatoid arthritis

  • SLE

  • Serum Sickness

Type IV: Cell-Mediated or Delayed Hypersensitivity

• Delayed response by sensitized T lymphocytes

• Release of lymphokines, leading to inflammatory response

• Destruction of the antigen

• Examples:

  • Poison Ivy

  • Tuberculin test

  • Contact dermatitis

  • Allergic skin rash

Autoimmune Disorders

• Development of antibodies against own cells or tissues

• Autoantibodies are antibodies formed against self-antigens—loss of self-tolerance.

• Disorder can affect single organs or tissues or can be generalized.

• Examples:

  • Hashimoto thyroiditis, systemic lupus erythematosus, rheumatic fever, myasthenia gravis, scleroderma, pernicious anemia

Systemic Lupus Erythematosus (SLE)

• Type III Hypersensitivity

• Chronic inflammatory disease affecting a number of organ systems

• Characteristic facial rash—“butterfly rash”

• Affects primarily young women, with higher incidence in African Americans, Asians, Hispanics, Native Americans

• Large number of circulating autoantibodies against DNA, platelets, erythrocytes

• Formation of immune complexes, deposited into tissues, leading to inflammation and necrosis

• Vasculitis develops in many organs, impairing blood supply to the tissues

• Signs and symptoms vary because of organ involvement but commonly include:

  • Arthralgia, fatigue, malaise

  • Cardiovascular problems

  • Polyuria

Immunodeficiency

• Partial or total loss of one or more immune system components

• Predisposition to the development of opportunistic infections and increased risk of infection and cancer

• Primary deficiencies: Basic developmental failure somewhere in the system

• Secondary or acquired immunodeficiencies: Loss of the immune response from specific causes, can occur at any time during the life span

  • Infections, splenectomy, malnutrition, liver disease, immunosuppressant drugs, radiation, chemotherapy (cancer)

Acquired Immunodeficiency Syndrome (AIDS)

• AIDS—chronic infectious disease caused by the human immunodeficiency virus (HIV)

• HIV destroys helper T cells—CD4 lymphocytes, leading to loss of immune response

• Increased susceptibility to secondary infections and cancer

• Prolonged latent period

• HIV-positive individual: Virus is known to be in the body but with no evidence of immunosuppression

• AIDS: Marked clinical symptoms, multiple complications

  • Individual often identified as HIV-positive before development of AIDS

The Agent

• Human immunodeficiency virus (HIV)

• Retrovirus, member of the subfamily lentavirus

• HIV-1: Major cause of AIDS in US and Europe

• HIV-2: Major cause of AIDS in central Africa

Transmission

• Bodily fluids:

  • Blood

  • Semen

  • Vaginal fluids

Clinical Signs and Symptoms

• Generalized effects:

  • Lymphadenophathy

  • Fatigue and weakness

  • Headache

  • Arthralgia

  • Gastrointestinal effects primarily due to opportunistic infections

• Encephalopathy: Sometimes called AIDS dementia due to direct infection of brain cells by HIV

Secondary Infections

• Primary cause of death

• Frequently multiple, more extensive and severe than usual

• Lungs: Pneumocystis carinii

• Herpes simplex: Cold sores

• Candida: Involves mouth and often esophagus

• Tuberculosis

Cancer and AIDS

• Increased incidence of all cancers

• Unusual cancers are often markers for AIDS:

  • Kaposi sarcoma: Affects the skin, mucous membranes, and internal organs

  • Non-Hodgkin lymphoma: Purple or brown nonpruritic, painless patches that eventually become nodular