Microbiology- Chapter 16 (Disorders In Immunity

Front 1

What is Immunopathology?

Back 1

Immunopathology- the path of diseases associated with overreactivity or underreactivity of the immune system

Front 2

What is hypersensitivity?

Back 2

Allergy.

-Sometimes human body responds to antigens other than pathogenic microgrganisms- this is hypersensitivity- allergy

Front 3

Fill in the blank

Antigens causing allergies are called ____

Back 3

Allergens

Front 4

What are the two types of allergens?

Back 4

-Exogenous: pollen, mold, dust mites, cat and dog antigens, insect venom, etc.

-Endogenous: self-tissues (autoimmunities)
-

Front 5

True or False.

Allergies occur in persons who have been sensitized (previously exposed) to some allergen

Back 5

True

Front 6

Name the types of allergic reactions.

Back 6

-Type I
anaphylactic reactions (IgE)

-Type II
antibody mediated cell damage (IgG; IgM)

-Type III
immune complex

-Type IV
delayed hypersensitivity (T-cell)

Front 7

Describe the portal of entry of allergens.

Back 7

- Epithelial portals of the respiratory tract, gastrointestinal tract and skin.

Note: The muscosal surfaces of the gut and respiratory system present a thin, moist surface that is normally quiet penetrable.

Front 8

What are the mechanisms of type 1 Allergy.

Back 8

-Initial encounter with an allergen (sensitizing dose)

-Allegen is carried with lympathtics to lymph nodes- B nodes are activated and proliferate into plasma cells

-IgE is produced – binds to the mast cells

-Mast cells are located in the connective tissue throughout the body

-No symptoms

-The second contact with allergen

-When the allergen encounters two adjacent antibody molecules already attached to the surface of the mast cell, it will bridge over two antibodies

-This will trigger the mast cell to release mediators – (histamine, serotonin, leukotrien..)

–degranulate causing allergy symptoms

-Targets of the chemical mediators include: skin, upper respiratory tract, gastrointestinal tract, and conjunctiva

-Symptoms include: rashes, itching, redness, rhinitis, sneezing, diarrhea, shedding of tears

Front 9

Describe the second contact in type 1 allergy.

Back 9

-The second contact with allergen
-When the allergen encounters two adjacent antibody molecules already attached to the surface of the mast cell, it will bridge over two antibodies
-This will trigger the mast cell to release mediators – (histamine, serotonin, leukotrien..) –degranulate causing allergy symptoms
-Targets of the chemical mediators include: skin, upper respiratory tract, gastrointestinal tract, and conjunctiva
-Symptoms include: rashes, itching, redness, rhinitis, sneezing, diarrhea, shedding of tears

Front 10

What are the mediators that the mast cells release?

Back 10

This will trigger the mast cell to release mediators – (histamine, serotonin, leukotrien..) –degranulate causing allergy symptoms

Front 11

What is the fastest reacting mediator?

Back 11

Histamine

Front 12

What are the effects of histamine?

Back 12

Effects of histamine:

-Constrict smooth muscle of bronchi- labored breathing

-Dilates blood vessels – hypotension, tachycardia, shock

-Increases the permeability of blood vessels (swelling and redness), and mucus secretion(runny nose)

Front 13

What are the two diseases associated with Type 1 Hypersensitivity?

Back 13

Hay fever- allergic rhinitis
-Reactions to inhaled polle, mold spores
-Symptoms: nasal congestion, sneezing, coughing

-Eczema : atopic dermatitis
-Sensitization: ingestion, inhalation, skin contact
-Symptoms: thickened skin, lesions

Front 14

Describe food allergy.

- What is affected
-mode of entry
- Symptoms
- Allergens

Back 14

-Mode of entry is intestinal
-Affected: skin, respiratory tract, gastrointestinal system
-Symptoms: eczema, rhinitis, asthma, anaphylaxis
-Food allergens: peanuts, fish, milk, shellfish…

Front 15

Describe drug allergy.

-Allergens

Back 15

Drug Allergy
-Some drugs can cause allergic reactions in some individuals (5-10% of patients)

-The drug allergens: antibiotics (penicillin) sulfa drugs, aspirin

Front 16

Anaphylactic reactions can occur in which 2 ways?

Back 16

Systemic (antigen is injected)

-Dilation of peripheral blood vessels throughtout the body –drop of blood pressure- shock
-Can be fatal within a few minutes
-Allergy to penicillin

Localized reaction (antigen is inhaled or ingested)

-itchy, water eyes, sneezing, coughing
-allergy to pollen, dust mites, mold spores, some food

Front 17

What are the diagnostic tests for allergies?

Back 17

Diagnostic tests include:

-Measuring the blood levels of tryptase (an enzyme released by mast cells)
-Differential blood cell count (increased levels of basophil and eosinophils- indicate allergy)
-Measuring the quantity of IgE immunoglobulin in blood
-Skin test – skin is injected with the pure allergen

Front 18

What are ways to deal with anaphylactic reactions?

Back 18

-Avoid contact with sensitizing agent
-Desensitization therapy (series of increasing doses)
-Carry at all times Epinephrine (adrenalin) –reverses the constriction of the airways

-Treatment:
-Drugs that block the actions of lymphocytes
-Corticosteroids – prevent synthesis of IgE
-Antihistamines

Front 19

What are the treatments for anaphylactic reactions?

Back 19

-Treatment:

-Drugs that block the actions of lymphocytes
-Corticosteroids – prevent synthesis of IgE
-Antihistamines

Front 20

How does desensitization work?

Back 20

How does it work?

-Theory:
-The injected allergen causes IgG antibodies to be produced (instead of IgE), they bind to allergens -Allergens removed before they react with IgE

Front 21

What is type 2 Hypersensitivity and when does it occur?

Back 21

Involves complement assisted destruction of cells

-Includes: ( occurs when)
-Transfusion reactions
-Some types of autoimmunity

Front 22

What are the four blood groups?

Back 22

A

B

AB

O

Front 23

What are blood groups based on?

Back 23

based on the antigens present on the surface of the red blood cells

Front 24

True or False.

Blood does not contain antibodies against “non-self” blood type.

Back 24

FALSE

Blood contains antibodies against “non-self” blood type
-Example: Type A contains antibody against type B

Front 25

Which blood group can be used as a universal donor?

Back 25

O can be sued as universal donor

Front 26

Which blood group is a universal recipient?

Back 26

AB type is universal recipient

Front 27

What happens when there is transfusion of the wrong blood type?

Back 27

-Transfusion of the wrong blood type results in destruction of red blood cells -systematic shock and failure of kidneys

Front 28

What is the Rh http://www.flashcardexchange.com/mycards/add/1259201factor?

Back 28

Rh factor is another antigen found on the red blood cells
-Present in 85% and absent in 15% of humans
-Blood typing contains information on presence/absence of Rh factor (A+, B-)

Front 29

What happens when the mother has Rh - and the unborn baby has Rh +?

Back 29

Hypersensitivity can occur when Rh- mother is sensitized with Rh + red blood cells of their unborn baby

-In the case of 2nd pregnancy this can cause hemolysis of red blood cells of the newborn- hemolytic disease

-Can be prevented by passive immunization of a mother with antibodies against Rh factor- injected right after delivery

Front 30

What is Type 3 Hypersensitivity?

Back 30

Type 3 involves the reaction of soluble antigen with antibody and deposition of the resulting complexeses in basemenrt membranes of epithelial tissues.

Causes immune complex reaction or disease.
Two diseases:
- Arthus reaction
- Serum sickness

Front 31

Type IV Hypersensitivity is also known as what?

Back 31

-Also known as delayed hypersensitivity (one to several days following the 2nd contact)

Front 32

Describe Type IV Hypersensitivity.

What is involved in it and in what circumstances does it occur?

Back 32

Also known as delayed hypersensitivity (one to several days following the 2nd contact)
-Involves T-cells

-Include
-Delayed allergic reactions to infectious agent
-Contact dermatitis
-Graft rejection

Front 33

Describe the diagnostic technique for detecting tuberculosis.

Back 33

Infectious Allergy
-Tuberculin reaction- diagnostic technique for detection of tuberculosis

-Tuberculin (extract of Mycobacterium tuberculosis) is injected intradermally

-A person sensitized to tuberculosis will respond with a raised red bump

Front 34

Autoimmune diseases fall under which types of allergy?

Back 34

Fall into category of type II or type III hypersensitivity

Front 35

what are autoimmune diseases and why do they occur?

Back 35

Autoimmune diseases

-Response of immune system against one’s own organs – involves autoantibodies and T cells
-Can target several major organs (systemic) or only one organ

Front 36

What is Rheumatoid arthritis?

Back 36

Autoimmune disease

Rheumatoid arthritis – IgM, IgG and complement are deposited in the joints
-Damage to the cartilage in the joints- loss of functioning and mobility

Front 37

What is Lupus?

Back 37

Most severe autoimmune disease

Production of antibodies against different organs (kidneys, bone marrow, skin, nervous system, joints…)

-The etiology is unknown
-Role of hormones – 90% of cases in women
-Viral infection not excluded

*characteristic rash across the face

Front 38

What is Multiple sclerosis?

Back 38

Autoimmune disease

Neurological disease

-T-cells and macrophages attack the myelin sheath of nerves

-Progression slow

-The most severe symptoms – paralysis

-Etiology – may involve an infective agent

Front 39

Why do immunodeficiency diseases occur?

Back 39

Immunodeficiency Diseases:
-Components of the immune responses are absent

-Can be caused by inherited abnormalities
-Infections (AIDS)
-Chemotherapy
-Radiation

-Due to:
-Lack of B and T-cells
-Congenital absence of thymus
-High susceptibility to microbial infections
-Lack of antibody production