Module 11: Alterations of the Immune System

Question 1

Type I Hypersensitivity

Answer 1

• “Immediate Hypersensitivity”
• IgE is produced by the immune system in response to environmental proteins such as pollens, animal danders or dust mights
  
  • IgE binds to mast cells and basophils which contain histamine granules that are released in the reaction and cause inflammation
• i.e. bronchial asthma
  
  • allergic rhinitis, allergic dermatitis, food allergy, allergic conjunctivitis, and a_naphylactic shock_

Question 2

Systemic Anaphylaxis

Answer 2

• severe, life threatening Type 1 immediate hypersensitivity reaction.
  
  • within minutes:
    
    • utching, urticaria, bronchioconstriction, skin erythema, laryngeal edema, tongue swelling, and angioedema
    • widespread vasodilation:
      
      • drop in blood pressure, vascular shock →anaphylactic shock
      • may loose consciousness
  • requires medical monitoring, immediate epinephrine

Question 3

Allergic Rhinitis

Answer 3

• allergen exposure causes symptoms related to inflammation of nasal cavity
  
  • vasodilation, smooth muscle contraction of bronchioles, mucus hypersecretion
    
    • watery eyes, sneezing, conjunctivities, rhinorrhea, coughing, bronchospasms, nasal polyps
    • white or clear secretions, IgE presence
  • associated with athma, sinusitis, respiratory infections

Question 4

Type II Hypersensitivity Reactions

Answer 4

• Type II or Cytotoxic-mediated response
  
  • IgG and IgM mediate cytotoxic mediated response against cell surface and extracellular matrix proteins
  • the immunoglobulins or antibodies involved in this type of reaction damages cells by activating the complement system or by phagocytosis
  • type II hypersensitivity reactions can be seen in immune thrombocytopenia, autoimmune hemolytic anemia and autoimmune neutropenia

Question 5

Management of of Hypersensitivity Reactions

Answer 5

• avoid the allergen
• tx of immediate hypersensitivity rxns = IM adrenaline, oxygen, IV antihistamine, support blood pressure with IV fluids
• corticosteroids, leukotriene antagonists
• omalizumab is a monoclonal antibody that interacts with the binding site of the high affinity IgE receptor on mast cells
  
  • Type I hypersensitivity reaction

Question 6

Autoimmune Disorder Definition

Answer 6

• T-Cells or Ig’s react to own body
• loss of self-tolerance
• damage to own tissues and organs
  *

Question 7

Autoantibody Definition

Answer 7

• antibodies against body’s own tissues

Question 8

Two types of Autoimmune disorders

Answer 8

1. sensitivity to your own organs or generalized tissues
   
   1. ex. Type 1 Diabetes–sensitivity to your pancreas
   2. ex. Multiple sclerosis – sensitivity to your myelin
   3. ex. systemic lupus erythematosus –generalized
2. Can begin with an infectious agent that has antigens similar to molecules of your self-antigens
   
   1. ex. Rheumatic fever: begins with strep throat (GABHS), forms Ig’s that attack myocardium especially heart valves because those antigens are similar to antigens of GABHS

Question 9

General Treatment of Autoimmune disorders

Answer 9

• imunosuppressives
• treat symptoms of the autoimmune disorder
  
  • diabetes mellitus type I = give insulin
  • arthritis = NSAIDS

Question 10

Define: Immunodeficiency Disorder

Answer 10

• disorders that suppress or weaken the immune system, innate defenses, adaptive defenses or both

Question 11

Types of Immunodeficiency Disorders

Answer 11

1. primary/congenital: genetically linked (many are X-linked)
   
   1. mutation
2. Secondary/acquired: associated with another condition that is immunosuppressive
   
   1. lymphoma, leukemia, HIV, stress, malnutrition

Question 12

SCIDs

Answer 12

Severe Combined Immunodeficiency

Type of Primary Immunodeficiency

• genetic, rare, many X-linked
• dysfunction of Tcell development
  
  • dysfunction of B-cell activation of T-cells
• usually diagnosed by 3 months due to multiple infections and failure to thrive
• life threatening
• **live-virus administration can be fatal**
• treatment:
  
  • bone marrow transplant

Question 13

DiGeorge Syndrome

Answer 13

• Primary immunodeficiency
• Autosomal Dominant
• genetic deletion of chromosome 22q11
• absent thymus
  
  • no T-cells, no CD4s
• multiple organ defects:
  
  • cardiac abnormalities
  • parathyroid gland maldevelopment
  • facial abnormalities
• Treatment:
  
  • can transplant thymus gland
  • see lots of specialists
  • cardiac defects can be fatal if not treated

Question 14

Combined T cell and B cell disorders

Answer 14

• DiGeorge Syndrome
• Wiskott-Aldrich Syndrome
  
  • x-linked recessive
• Ataxia Telangiectasia
  
  • Ataxia refers to uncoordinated movements, such as walking. Telangiectasias are enlarged blood vessels (capillaries) just below the surface of the skin.

Question 15

Rule of 2/3s

Answer 15

• For children under the age of 3 years:
  
  • 2/3 of WBC should be lymphocytes
  • 2/3 of lymphocytes should T cells
  • 2/3 of T cells should be CD₄ cells
• For someone older than 3 years of age:
  
  • 2/3 of WBC should be neutrophils
  • 2/3 of lymphocytes should be T cells
  • 2/3 of T cells should be CD₄ cells

Question 16

X-linked Agammaglobulinemia

Answer 16

• X-linked autoimmune disease
• “no IGG in the blood”
• 1:200,000 live births
• no/few B cells, normal T cells
• no tonsils, small lymph nodes
• usually not diagnosed until after 4 months when maternal immunity wanes

Question 17

HLA

Answer 17

• human leukocyte antigen system
  
  • this is the major histocompatibility complex (MHC) in humans
• important part of immune system that is controlled by genes located on chromosome 6
  
  • it encodes cell surface molecules specialized to present antigenic peptides to the T-cells
• HLA on a transplant organ must be similar to receiver of organ to prevent rejection

Question 18

Type II hemolytic disease of newborn

Answer 18

• occurs when you have repeated hemolytic disease of a newborn
• IgG reacts to Rh an innocuous rbc antigen
  
  • Rh+ baby born to Rh- mother first time = no issue
    
    • but mother will develop Rh antibodies if she does not receive treatment
  • if mother develops Rh antibodies from first pregnancy, can cross the placent and the baby will kill its own rbcs
• Prevention: treat mother with antibodies to Rh antigen right after birth→ mother will not mount an immune response and create her own antibodies