Chapter 16 pt 1

Hypersensitivity

1) Type 1: immediate reaction. Ex: Peanut butter allergies -Allergic reactions -IgE and Histamine 2) Type 2: Antibody Mediated. -Ex: someone is given the wrong blood type and antibodies react to it. -IgG and Complement 3) Type 3: Immune complex. Rheumatoid Arthritis 4) Type 4: Cell-mediated; cytotoxic. -Skin grafts by someone else that the body rejects

Anaphylaxis

A sudden respiratory and circulatory disruption that can be fatal. -A greatly amplified response of chemical mediators with every exposure -Sensitivity can last for decades -Can be fatal extremely quickly (within 15 minutes) -Restricted airway/dilation of the blood vessels -Ex: injection of certain antibiotics, bee stings, etc.

Chemical Mediators

Cytokines: the principal chemical mediators produced by mast cells and basophils. -Histamine -Serotonin Cause bad things to happen: -Reactions in smooth muscle -Airways constrict -Vessels dilate (edema) -Drops in BP

Portals of Entry

Proteins are more allergenic than carbohydrates, fats, or nucleic acids. 1) Inhalants: airborne environmental allergens 2) Ingestants: allergens that enter by mouth 3) Injectants: Side effect of drugs/other substances or naturally through venom from stings 4) Contactants: allergens that enter through the skin

Hemolytic Disease

Rh Factor incompatibility between mom and baby. -Mom is Rh- and baby is Rh+. -During birth, placenta breaks away and mom is exposed to baby's blood. -First exposure: Rh factor causes T and B Cells to produce antibodies, stored and wait (memory cells) -Second exposure: (second child). Mom has the antibodies for Rh+. (IgG can cross the placenta and attacks the baby's blood cells). Baby is in distress (hemolytic newborn). -Blood is being broken down due to the complement proteins, baby's kidneys get clogged up. Treatments: -If mom is Rh-, she gets RhoGAM, which is anti Rh antibodies that binds to them, keeping them from crossing the placenta.

Asthma

Episodes of impaired breathing due to severe bronchoconstriction -Sensitive to minute amounts of allergen exposure Symptoms: -Shortness of breath to suffocation -Wheezing -Cough -Inflamed respiratory tract

Atopic Dermatitis

Intense, itchy inflammatory condition of the skin. (Eczema) -Can begin in infancy and progress into adulthood -Ingestion, inhalation, or occasionally skin contact Symptoms: -Dry, scaly thickened skin -Face, scalp, neck, inner surface of limbs and trunk

Type 2 Hypersensitivities

Reactions that involve complement, IgG, and IgM, resulting in lysed foreign cells. -Blood transfusions: when markers on the transfused designate them as foreign. -These markers give us A, B, O, etc -Also happens with implanted organs rejected as foreign -Immune system doesn't know difference between a good foreign and a bad foreign -Also auto immune diseases (self cells).

Type 1 Allergies

Two levels: 1) Atopy: chronic, local allergy. -Ex: hay fever, asthma, etc 2) Anaphylaxis: systemic, sometimes fatal reaction

Hygiene Hypothesis

Type 1 allergy is due to the lack of immune system exposure to antigens early in life (immune system doesn't develop) -Babies born to moms with allergies by C section are less exposed to germs than babies born vaginally to mom's with allergies. More susceptible to allergies.

Drug Allergy

Virtually any tissue can be affected -Reactions range from mild atopic reactions to fatal anaphylaxis Common: -Antibiotics (penicillin) -Synthetic antimicrobials (sulfa drugs) -Aspirin -Opiates

Blood Types

-If you're type A, A antigen is present, and you have antibodies in your plasma against B. B and T cells specific for that B antigen. When you encounter that B antigen, you produce anti B antibodies. -If you have type B, you have anti A -Type O has both anti A and Anti B (universal donor) -If you have AB, has neither anti A nor Anti B (universal recipient) -If wrong type is given, antibodies attack donor cells. -Big problem if you have lysing blood cells

First exposure

1) Allergen penetrates portal of entry 2) Lymph Vessels carry the allergen to the lymph node 3) Clones of the B cells recognize allergen, are activated, and proliferate into plasma cells. 4) Plasma cells produce IgE, the antibody of allergy (people predetermined genetically to produce IgE instead of IgG or IgM) -IgE has an Fc region (base of the Y) with a great affinity for mast cells and basophils 5) The binding of IgE to mast cells or basophils causes the reactions that occur upon repeat exposure to the allergen

Allergy Diseases

1) Atopic Disease: -Hay fever (rhinitis) -Asthma -Atopic dermatitis (Eczema) 2) Food allergy: systemic 3) Drug Allergy: systemic 4) Anaphylaxis: systemic and very serious

Allergy Treatment

1) Avoid Allergen -Ex: wearing bracelet saying to not administer penicillin 2) Steroids prevent the synthesis of IgE by plasma cell 3) Monoclonal antibodies inactivate IgE after it has formed 4) Cromolyn (a drug) acts on the surface of a mast cell, preventing degranulation 5) Antihistamines and aspirin counteract the effects of cytokines on target cells

Hyposensitivity

1) Primary Immunodeficiency: A genetic disorder inherited. Have it from birth. 2) Secondary Immunodeficiency: Caused by something else. Ex: HIV causes immune deficiency

Allergy Vaccines

Also known as desensitization or hyposensitization. -Controlled injections of the allergen. Two theories: 1) Injection causes production of IgG antibodies which remove allergen from system before they can bind to IgE on a mast cell, preventing an allergic reaction. 2) Allergens are usually inhaled, so by being delivered via injection, allergens can combine to IgE before it can bind to mast cells. -IgE antibodies before they bind to the mast cells. -No degranulation problem.

Rh Factor

Also known as the D antigen. -If you're A+, you have the D antigen. -If you're A-, you don't have the D antigen. (positive means you have it) -positive is dominant, meaning a person inheriting at least one Rh gene will be Rh+

Allergy

Altered reactivity or exaggerated immune response that causes un-warranted inflammation. -Immediate onset associated with exposure to a specific antigen (allergen) -Antigens do not cause noticeable reactions in non-allergic individuals. -Hypersensitivity: similar to allergy, but a more delayed reaction

Allergy Drugs

Block the progress of the allergic response between IgE production and symptoms. 1) Corticosteroids: inhibit lymphocytes 2) Antihistamines: bind to the histamine receptors on target organisms, blocking the histamine from binding. 3) Aspirin 4) Cromolyn: prevents degranulation 5) Drugs that inactivate IgEs 6) Epinephrine: reserves the constriction or airways. -Epi pen -A short term fix to slow down a reaction

Second Exposure

IgE primed cells can remain in the tissues for years. -No latent period. Immediate response. 1) Allergen contacts the IgE primed mast cells, they bind together, stimulating degranulation 2) Chemical mediators are released and diffuse into the tissues and blood stream 3) Cytokines give rise to local and systemic reactions -Inflammation -Causes problem

Mast Cells and Basophils

Located throughout the connective tissue of all organs (not found in the blood stream or lymphatic system). 1) Bind to the Fc region on the IgE -Each cell carries 30,000 - 100,000 IgE receptors -Cell becomes coated in IgE 2) Degranulate: granules release their chemical transmitters into the surrounding material -IgE receptors trigger the release of inflammatory cytokines from granules 3) Cell primed with IgEs on its surface goes into the tissues and lives for very long. -At this point, person is allergic

Food Allergy

Most common food allergens: -Peanuts, fish, cow's milk, eggs, shellfish, and soybeans. Gastrointestinal symptoms: -Vomiting, diarrhea, and abdominal pain Other Symptoms: -Eczema -Hives -Rhinitis -Asthma -Occasionally anaphylaxis

Symptoms

Of degranulation. -Headache -Increased blood flow -Skin Manifestations (rash/hives) -Increased peristalsis of intestine (diarrhea, vomiting) -Runny nose -Asthma

Skin Testing

Patient's skin is injected, scratched, or pricked with a small amount of pure allergen extract. -Allergist maps the skin, examining for inflammatory response -Unreliable for food allergens

Hereditary

People are born only with a generalized susceptibility to allergies. -Not born allergic to a specific antigen -People are just more prone to produce IgE antibodies. -Age, infection, and geographic location influence risk for allergies (Children that grow up in rural areas/large families: have less rates of allergy) -Hygiene Hypothesis

Regulation of Immunity

The immune system must be carefully controlled. Disorders of the immune system can be due to: -Under-reaction: immune system is damaged/not working properly and individual stays sick -Over-reaction: Immune system is too effective and damages self cells

Hay Fever

The inflammation of nasal passages as a reaction to pollen or molds. -Targets respiratory membranes -Can be year round or only parts of the year Symptoms: -Nasal congestion -Sneezing -Coughing -Mucous secretions -Itchy, red, and teary eyes -Mild bronchoconstriction

Immunopathology

The study of disease states associated with over reactivity or under reactivity of the immune response. -Over reactivity: person encounters antigen and immune system over responds to it. -Exogenous: Can be any kind of foreign cell/protein -Endogenous: immune system overreacting to a self cell. Hyposensitivity Diseases: Immune function is incompletely developed, suppressed, or destroyed

Wrong Transfusions

Transfusions of the wrong blood type can result in a severe reaction. -Massive hemolysis when donated RBCs react with recipient antibody and trigger the complement cascade -Destruction of RBCs leads to systemic shock and kidney failure (clog up kidneys) -Often results in death