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9 Cards in this Set

  • Front
  • Back

5 Types of Hypersensitivity

I. Anaphylactic (immediate)


II. Cyctotoxic (hours - days)


III. Complex-mediated (hours - days)


IV.Cell-mediated (two - three days)


V.Stimulatory

Type I - Anaphylactic
  • Immediate, IgE mediated



  • Antigens binds to IgE on mast cell



  • Mast cell degranulation;

- Direct injury


- Clustering and cross-linking of IgE receptors




  • Release of Histamine

- Contraction of smooth muscle


- Dilation of capillaries




Example: Bee Sting

Type II - Cytotoxic
  • Antigen/antibody combination promotes agglutination, opsonic adherence & c' - lysis



  • Haemolytic Disease of the Newborn (HDNB)
- Rh-ve woman with Rh+ve fetus

- Woman becomes sensitized (forms anti- Rh+ve antibodies)


- Next Rh+ve pregnancy, maternal antibodies attack fetal RBC




Transfusion reaction:


  • Haemoglobulinuria - RBC lysed in urine
  • Haematuria - RBC settle with clear urine

Type III - Immune-complex mediated
  • Deposited in vascular epithelium
  • Inflammation leads to Tissue damage

- Aggregate platelets;


-provide vasoactive amines


-form microthombi leading to local ischemia




- Arthus skin reaction; swelling & redness


- Farmer's lung; Antigen from mouldy hay

Type IV - Cell Mediated Immunity (CMI)

Delayed Type





  • Leads to T-cell and macrophage granulomas

> Mantoux reaction (Tuberculin)


- Erythema and induration after several hrs.


- Reaches maximum at 48-72 hrs.




> Tissue Transplant Rejection

Type V - Stimulatory

Antibody reacts with a key surface component


- Acts as agonist leading to stimulation of cell





  • Graves Disease

- Thyroid-stimulation Hormone (TSH) binds to receptor on thyroid epithelial cell


- Adenylyl cyclase is activated and cAMP is generated to stimulate thyroid hormone production


- Thyroid-stimulating antibody is an autoantibody that mimics TSH


- Continuous secretion of antibody = Hyperthyroidism

Ligand Immunoassays
  • Labelled ligand so can measure event



  • Ab usually binds the ligand(can Ab, drug, etc)

Radio Immunoassays (RIA)
  • Competetive binding assay



  • Radio labelled with 125-Iodine (125^I) antigen

  • Sample forced to compete for limited number of antibodies

  • Separate Ab-boud and free Ag prior to measuring ICX radioactivity in gamma counter

Enzyme-Linked ImmunoSorbent Assay (ELISA)
  • Enzyme attached to one of reagents
  • Substrate added to get colour change
  • Meaure colour change in plate reader



- Test for antigens


- Test or presence of Abs