Microbiology Ch.14 Flashcards
Function of immune system
protect the body from pathogens. To do this it must distinguish self from non self
Graft/organ rejection
our immune system trying to “protect” us from foreign invasions
* skin graft, kidney transplant, transfusion Disorders in Immunity
Allergen
Ag (usually innocuous) that causes an over-reactive immune response
Allergy symptoms can affect
airways, sinuses/nasal passages, skin, digestive system. 20% of allergies caused by dried feces of dust mites
Inhalants:
airborne environmental allergens such as pollen, house dust, dander, or fungal spores
Ingestants:
allergies triggered by drugs, vaccines, or hymenopteran (bee) venom
Contactants:
allergies that enter through the skin; many are type IV (delayed) hypersensitivities
Anaphylaxis:
severe, potentially life-threatening allergic reaction occurring shortly after (within seconds to a few minutes) exposure to allergen
Signs & Symptoms of Anaphylaxis
Loss of consciousness, Drop in blood pressure, Severe shortness of breath, Skin rash, Lightheadedness, Rapid, weak pulse, Nausea and vomiting
Chemical mediators are released that cause
shock due to vasodilation and smooth muscle contraction, bronchial constriction
Localized Anaphylaxis
- Reactions include sneezing, tears, watery (red, itchy) eyes, breathing
difficulty, rash, hives - Symptoms depend on the route of the allergen (inhalation, direct
contact, etc.) - If allergen enters bloodstream it can cause widespread symptoms
Systemic Anaphylaxis
- Results from massive release of mast cell granules in a short time
- Can lead to anaphylactic shock
- Damage to various organs
- Condition may be fatal (usually due to asphyxiation)
Effects on our immune
system
Sanitization of water and food, medical advances, vaccines,
increase in personal hygiene
Effect of Breast Feeding on Immunity
- Newborns breast fed exclusively for the first 4 months have a lower
risk of asthma and eczema - Cytokines and growth factors in human milk act on the baby’s gut
mucosa to induce tolerance to allergens
Human Microbiome Project:
600 species of bacteria can be
transferred to infants through breast milk
Immediate Hypersensitivity
- IgE mediated mast cell degranulation
- Triggered by interaction between allergen & IgE bound to
mast cell, basophil or eosinophil
Allergic rhinitis (Hayfever)
mild allergy to inhaled Ag, resulting in sneezing, runny nose, congestion, nasal irritation
Allergic conjunctivitis
occurs if allergen affects the eyes, can result in tears, itching, inflammation in the eye
Allergic asthma
reactions are shortness of breath, wheezing, bronchial constriction, smooth muscle contraction surrounding airways
immediate reaction
occurs within a few minutes of injection
Late phase reaction
occurs 6-8 hours after immediate reaction subsides, involves
spreading of the swollen tissues beyond the site of injection
Epinephrine
acts quickly to improve breathing, stimulate the heart, raise dropping blood pressure, reverse hives,
reduce swelling of face, lips, throat
Epi-pen
is used in emergencies to treat very serious allergic reactions to insect stings/bites, foods, other
substances
Allergy March
individuals experience different Type I Hypersensitivities, from infant into adulthood, in a somewhat “ordered” sequence
Allergy March example
GI tract (food allergy), Eczema (atopic dermatitis), Asthma, Hayfever (seasonal allergy,
rhinitis, conjunctivitis)
An IgG mediated immune
Type 2 hypersensitivity
response to small reactive molecules that become bound to cell surfaces, making the
new cell appear as foreign
* B cells are stimulated to make IgG antibodies against the new
epitope
Ag-Ab complex formation
Binding of IgG to the modified cells
ABO blood groups
transfuse with compatible blood type or get Type II reaction, blood type determined by oligosaccharide attached to glycolipid on RBC surface
Core structure:
lipid ceramide attached to an oligosaccharide of
Glucose-Galactose-N-acetyl galactosamine-Galactose-Fructose
Group A
A Ag and B Ab
Group B
B Ag and the A Ab
Group AB
A and B Ags but neither A nor B Ab
Group O
no A or B Ags but has both A and B Ab
Type O blood
Universal Donor, can
donate blood to anybody
Type AB+ blood
Universal Recipient, can
receive blood from all
blood types
Immune Complex Mediated Hypersensitivity (type 3)
When Ab combines with its specific Ag, immune complexes are formed
Type III hypersensitivity primarily mediated by
IgG and IgM, reaction can
take hours, days, or even weeks to develop
Type III reactions can occur when
Abs or other proteins derived from non- human animal species given therapeutically Ex. Diabetics injected with bovine or porcine insulin may result in a reaction
Local Immune Complex Disease or Arthus Reaction
- immune complexes are formed locally in the tissues (skin), an acute response to second injection of drugs, vaccines; inflamed blood vessels in area of injection
- Within a few hours area hot, red, painful
Systemic Immune Complex Reaction
- systemic injury occurs when Ag-Ab complexes circulate in blood, settle in vascular tissues of various organs (kidneys, heart, skin, joints
- Named for condition in soldiers after repeated injections of horse serum to treat tetanus
Systemic Lupus Erythematosus
Ag-Ab complex deposit mainly in the kidneys, skin, joints
Post-streptococcal Glomerulonephritis
While fighting Strept infection,
patient makes Ab that reacts against pathogen but also cross-reacts with glomerular Ag, causing Ag-Ab complexes to lodge in glomeruli
Drug Induced Serum Sickness
Drugs act as hapten, combine with tissue protein in host, induce immune responses against the drug-host protein complex
Farmer’s Lung and Bird fancier’s disease
Pulmonary diseases resulting from
inhalation of bacterial spores, (avian) fecal proteins
Rheumatoid arthritis
chronic inflammatory disorder affecting the joints
T cell mediated (type 4)
Involves interaction of activated T cells releasing cytokines & chemokines, summoning monocytes, macrophages, cytotoxic T cells that result in a local inflammatory response
Contact
Occurs after sensitization with simple chemicals (ex. nickel,
formaldehyde), plant materials (poison ivy), some cosmetics, soaps
Tuberculin
*Occurs due to sensitization of soluble Ags of microorganisms during many infectious diseases
Mycobacterium tuberculosis, Leishmania tropica, Mycobacterium leprae
Mantoux reaction to test for TB:
a small amount of Ag injected beneath the skin of a person previously exposed to M. tuberculosis
T Cells and Their Role in Organ Transplantation
Transplantation or grafting of organs and tissues is a common
medical procedure
* Although it is life-giving, it is plagued with the natural tendency of lymphocytes to seek out and destroy foreign antigens (Graft
Rejection)
Autograft
tissue transplanted from one site on an individual’s body
to another site
Isograft
tissue from identical twin is used
Allograft:
exchanges between genetically different individuals belonging to the same species; the most common types of grafts
Xenograft
a tissue exchange between individuals of a different
species
Autoimmunity
individuals actually develop hypersensitivity to
themselves
systemic
involves several major organs
organ specific
involves only one organ or tissue
Primary
Immunodeficiencies result from genetic disorder (Congenital
immunodeficiency)
Secondary
Acquired immunodeficiencies result from infection by
immunosuppressive microbes (e.g., HIV)
B-cell defects (low levels of B cells and antibodies): (primary)
Agammaglobulinemia (X-linked, non-sex-linked)
* Hypogammaglobulinemia
* Selective immunoglobulin deficiencies
T-cell defects (lack of all classes of T cells): (primary)
Thymic aplasia (DiGeorge syndrome)
Combined B-cell and T-cell defects (usually caused by lack or abnormality of
lymphoid stem cell) (primary)
Severe combined immunodeficiency (SCID) disease
* Adenosine deaminase (ADA) deficiency
Complement defects
(primary)
Lacking one of C components
* Hereditary angioedema associated with rheumatoid diseases
Secondary immune deficiencies Natural cause
infections (AIDS) or cancers
* Nutrition deficiencies
* Stress
* Pregnancy
* Aging
Secondary immune deficiencies
immunosuppressive agents
- Irradiation
- Severe burns
- Steroids
- Immunosuppressive drugs
- Removal of spleen
Molecular mimicry:
Microbial Ag with molecular determinants similar to
human cells can induce the formation of autoantibodies
Gut Microbiome:
altered microbiomes (use of antibiotics, less exposure
to being outdoors, bad diet) increase in autoimmunity
Graves’ disease
Attachment of autoantibodies to receptors on thyroxin-secreting
follicle cells of the thyroid gland
* Abnormal stimulation of these cells causes over- production of
the thyroid hormone and the symptoms of hyperthyroidism
Type I diabetes
Molecular mimicry has been implicated in the sensitization of
cytotoxic T cells to attack and lyse insulin-producing cells
* Reduced amount of insulin underlies the symptoms of this
disease
