Transcript The Immune System

The Immune System
Immune System Diseases
Non-Specific Immunity
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A wide variety of factors that provide nonselective opposition to the invasion of the
body by foreign protein-based substances
“Antigens”
Examples of Non-Specific
Immunity
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Inflammation
Mechanical Barrier , ie skin
Enzyme Activity
Interferons (chemical released in response
to ANY viral infection)
pH (acid and alkaline)
Specific Immunity
Response to a specific antigen
Two Types of Specific Immune
Actions
Immunoglobulins = Antibodies
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IgG - most abundant;crosses placenta
IgA – in plasma and mucus membrane
secretions
IgD - ?
IgE – increased with allergy
IgM - largest
Antigen-Antibody Complex Action
Antigen is rendered harmless by one or a
combination of the following
Precipitation
Agglutination
Opsonization
Neutralization
Complement
A series of protein enzymes that
attach to antigen-antibody
complexes involving IgG and
IgM
Immune Complexes – may damage host cells as well as antigen
Two Ways to Acquire Immunity
Hypersensitivity
Immune response that is not
needed and may cause harm
Hypersensitivity: Allergy
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Increased amounts of IgE
IgE and antigen attach to
mast cell
Mast cell releases
histamine and other
inflammatory mediators
Local – asthma, hay
fever, hives (urticaria),
GI/food allergy
Generalized –
Anaphylaxis
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Systemic release of
histamine causes low
blood pressure and swollen
airways
Is life-threatening allergic
reaction!
Hypersensitivity: Cytotoxic
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Complement attaches to IgG or IgM antigenantibody complex (now called an immune
complex)
Individual cells are lysed (most commonly
RBCs)
Examples: Rh disease (Erythroblastosis Fetalis),
Transfusion reactions
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Transfusion reaction may also cause anaphylaxis!
Hypersensitivity: Immune
Complex Mediated
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Immune complexes , ie IgG or IgM with
complement activated, cause damage to
large area of host tissue
Examples: Glomerulonephritis, Rheumatic
Fever
Hypersensitivity: Cell Mediated
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T-lymphocytes attack harmless antigenic
substances
May take 1-2 days to develop
Examples: transplant rejection, Tb skin
test
Immune Deficiencies
Congenital: Agammaglobinemia
Acquired:
 Malignancies of the bone marrow and
lymphatic system
 Chemotherapy
 Steroids
 AIDS
AIDS
Acquired Immune Deficiency
Syndrome
AIDS Etiology
Human Immunodeficiency Virus
(HIV)
HIV can be found in all body
fluids of infected persons
Transmission usually most common with
infected blood, semen, and vaginal
secretions
 Unprotected exposure to body fluids puts
everyone at risk, eg health care workers
High-risk practices:
 IV drug abuse
 Unprotected sex (includes anal sex)
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High Risk Groups
AIDS Pathology
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Virus attaches to the CD4+ protein on Thelper cells and destroys them
Decreased T-helper cell count makes the
patient prone to opportunistic infections,
malignancies not normally seen in patients
with intact immune systems, and direct
CNS destruction
AIDS Progression
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HIV infection – HIV+
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ARC – AIDS Related Complex
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Antibodies produced usually within 1-6 months of
exposure
The antibodies produced cannot control the virus!
Enlarged lymph nodes,chronic fever and fatigue,
weight loss
Full blown AIDS – opportunistic infections and
malignancies, and CNS damage
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Usually occurs when T-helper cell count drops to less
than 500 (usual count is 800-1200)
Some Opportunistic Infections
Seen in AIDS
Malignancies Seen in AIDS
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Kaposi’s Sarcoma
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Malignant nodules form on the skin and in the
mouth, lymph nodes, and internal organs
Squamos cell carcinomas in the mouth,
rectum, and uterine cervix
AIDS Treatment
Current drug regimes prevent the virus from
replicating. They control the virus but do not
destroy it!
These drugs are very costly and have many side
effects!
 Reverse Transcriptase Inhibitors and
Nucleoside Analogs
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AZT (Zidovudine), DDI (Didanosine), 3TC
(Lamivudine)
Protease Inhibitors
Fusion inhibitors
AIDS “COCKTAIL”
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Truvada
A combination of Tenofovir (Viread) and
Emtricitabine (Emtriva)
Works So well, it is being tried as a
vaccine
Implications for Health Care
Professionals
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Frequent Handwashing
Barrier Protection for potential body fluid
exposure
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Careful technique during invasive procedures
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Mask, gown, gloves, protective eyewear
The odds are in your favor!
HIV is not spread by casual contact!
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Handshakes, eating & drinking utensils, toilet seats,
etc do not transmit HIV
Hate the disease……..
But don’t hate the sick person!
Autoimmunity
antibodies form against body
tissues
Autoimmune Diseases
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Systemic Lupus Erythematosus (SLE or
“Lupus”)
Rheumatoid Arthritis
Multiple Sclerosis (MS)
Autoimmune diseases may be inherited,
caused by a drug reaction, reaction to a
virus, environmental factors, or idiopathic