Hypersensitivity & Autoimmunity

Hypersensitivity & Autoimmunity
Four Types of Hypersensitivity
 Type 1 – allergy (immediate)
 Type 2 – Cytotoxic, antibody-dependent
 Type 3 – Immune Complex Disease
 Type 4 – Delayed hypersensitivity, cell-mediated immune response, antibody
independent

B Cells – produces anti-bodies (immunoglobulins) when there is a reaction is occurring,
such as the invasion of bacteria or virus; multiple immunoglobulins are involved in a
reaction

Functionality of the Different Immunoglobulins
 IgG – major type in plasma; involved in memory response to antigens already
encountered
 IgE – allergic response
 IgD – involved in the primary response to a new sensed pathogen
 IgM – synthesized by B cells in the primary immune response
 IgA – 1st antibody synthesized in the primary immune response

Allergies (a Type I Hypersensitivity Reaction)
 Overreactive immunity with excessive inflammation in response to the presence of
antigens to which the patient has been previously exposed
 Degree of Reactions:
o Uncomfortable – itchy, watery eyes; sneezing
o Life-Threatening – allergic asthma, angioedema, anaphylaxis,
bronchoconstriction, circulatory collapse

Type I Rapid Hypersensitivity (Atopic Allergies)
 Increased production of IgE, which stimulates the release of histamines
 Examples – allergic rhinitis (hay fever), allergic asthma, anaphylaxis
 Causes:
o Inhaled (plant pollens, fungal spores, animal dander, house dust, grass,
ragweed)
o Ingested (foods, food additives, drugs)
o Injected (insect or other venom, drugs, biological substances, such as
contrast dyes)
o Skin or Mucous Membrane Contact (latex, pollens, foods, environmental
proteins)
 Types:
o Localized – reaction only occurs around antigen exposure
o Systemic – caused blood vessel dilation, bronchoconstriction, and
decreased cardiac output
 Rapid Hypersensitivity (medical emergency – anaphylaxis) –
causes angioedema (facial swelling) which can rapidly progress to
swelling in the throat compromising airway clearance
 Assessment
o Signs and Symptoms
This study source was downloaded by 100000842323853 from CourseHero.com on 10-25-2022 03:54:48 GMT -05:00


https://www.coursehero.com/file/171905325/Hypersentivity-and-Autoimmunitydocx/

,  Feelings of uneasiness, apprehension, doom
 Generalized itching, urticaria
 Erythema, angioedema
 Wheals or hives/urticaria
 Congestion, rhinorrhea, dyspnea, respiratory distress, SOB
o Acquire history and manifestations, comprehensive allergy history
o Diagnostic Tests
 CBC: Eosinophil Count – associated with an allergic response; levels
elevated
 Blood Test: total serum IgE
 Some tests can test for the specific type of IgE
 Skin Test – golden standard, quick results within the clinical facility
 Interventions
o Oxygen, if respiratory assistance is needed
o Epinephrine – for anaphylactic reactions; may have to give more than one
dose (patient usually are prescribed 2 pens); short-term treatment; ER visit
immediately following IM injection; can be injected through the clothes
o Encourage wearing a medical bracelet
o Antihistamines – Diphenhydramine (Benadryl), Cetirizine (Zyrtec),
Loratadine (Claritin) – first-line agents for seasonal allergies
o Corticosteroids – IV in anaphylaxis; Nasal spray in allergic rhinitis, can also
be given orally

Type II: Cytotoxic Reactions – the body makes special autoantibodies directed
against its own cells (NEED TO KNOW THE TYPES FOR THE EXAM)
 Hemolytic Anemias – involves lysis, ABO blood incompatibility (maternity – Rh
factors)
 Immune Thrombocytopenic Purpura – decreases number of platelets in the
blood; the immune system attacks and destroys platelets
o S/S: bruising, bleeding, pinpoint-sized reddish-purplish spots on the
lower legs
 Hemolytic Transfusion Reactions – blood incompatibility during a blood
transfusion
o S/S: back pain, blood urine, chills, fever, flank pain, skin flushing, fainting or
dizziness
 Drug-Induced Hemolytic Anemia – occurs when medication triggers the
immune system to attack RBCs
 Goodpasture’s Syndrome – primarily affecting the lungs and the glomerular in
the kidneys; autoantibodies attacking the small vessels causing infection
o Causes – renal failure
o S/S:
 Cough
 Dyspnea – SOB
 Edema and Weight Gain
 Hypertension and Tachycardia
 Decreased urinary output and blood in urine – kidney dysfunction
 Hemoptysis – coughing up blood; blood-stained mucus
 Glomerulonephritis – inflammation of the glomeruli: tiny filters that
remove waste and fluids from the blood
o Diagnostics
This study source was downloaded by 100000842323853 from CourseHero.com on 10-25-2022 03:54:48 GMT -05:00


https://www.coursehero.com/file/171905325/Hypersentivity-and-Autoimmunitydocx/