Vaccines and Hypersensitivity

Killed Microorganisms or Inactivated Viruses

• ex:

  • salk inactivated polio vaccine

  • rabies vaccine

  • influenza

Live-Attenuated Vaccine

• mutant form of live pathogen that grows poorly in human cells and is no longer pathogenic

Examples of Live Attenuated Vaccines

• Sabin oral polio vaccine 

• MMR

• chickenpox, zoster/shingles 

Subunit Vaccines

• purified single or mixed components 

  • toxoids or acellular pertussis

Toxoids

• type of subunit vaccine 

• inactivated toxins 

  • diphtheria and tetanus

Conjugate Vaccines

• protein-polysaccaride complex

Conjugate Vaccine Examples

• meningococcal

• newer Hib vaccine

• Prevnar 13 

Recombinant Vaccines

• gene cloned into another microorganism in vitro 

Recombinant Vaccine Examples

• Herpes zoster

• HPV

• hepatitis B

Thimerosal

• organomercury compound that was used as a preservative in vaccine

• was thought to be linked to autism 

Hypersensitivity

• heightened or unnecessary immune response to an innocuous environmental antigen 

Immediate Hypersensitivity

• antibody mediated

• within seconds to hours of second contact with allergen

Delayed Hypersensitivity 

• cell mediated 

• peak reaction time between 48-72 hours 

Allergen

• noninfectious environmental antigen that induces hypersensitivity reaction

What type of response is elicited in a type I hypersensitivity reaction?

• IgE antibody response upon sensitization

Type I Hypersensitivity

• fastest response

What doe cells bind to in a type I hypersensitivity response?

• allergen specific IgE

What does histamine do in type I hypersensitivity reactions?

• increases capillary permeability, skin itching, and muscle contractions 

What happens in the early phase of type I hypersensitivity?

• mast cell degradation within seconds

What happens in the late phase of type I hypersensitivity? 

• eosinophils, PMNs, and macrophages arrive and degranulare

• second release of mediators

What are localized effects of type I hyersensitivity?

• allergic rhinitis, asthma, dermatitis 

Angiodema

• diffuse swelling due to mast cell deeper in tissues 

What does the RAST test look for?

• measures allergen specific IgE

What does the RIST test look for?

• measures total serum IgE

What do allergy shots do?

• desensitization

  • repeated injections that help patient build up a tolerance to the allergen

Type II hypersensitivity

• cytotoxic

• mechanisms of cellular damage

• IgG or IgM produced and bind to cell surface molecules and perceive them as foreign 

Acute Hemolytic Anemia

• donor blood group transfers antigens not compatible with recipient 

Hemolytic disease of the newborn

• Rh- mother is exposed to Rh+ fetal RBC during birth 

• in next pregnancy IgG antibodies cross placenta and attack fetal RBC in utero

Drug Induced Hemolytic anemia

• caused by over 150 drugs

• ex: penicillin, NSAIDs

Myasthenia gravis

• autoantibodies produced against acetylcholine receptors on muscle fibers

Type III Hypersensitivity

• deposition of circulating immune complexes 

Arthus Reaction

• localized areas of painful erythmea and hard swelling

Serum Sickness

• patients who receive foreign serum or some medications 

Rheumatoid Arthritis

• IgM, IgG, or IgA against IgG Fc region