Diseases that arise from an overactive or exaggerated immune response. In other words, the body attacks itself.

A supressed or weakend activity in the immune system.

• Commonly called allergies.
• Local or generalized.
• Immediate and rapid.
• Reaction that results from a release of inflammatory molecules (histamine) in response to an antigen.
• Result from abnormal production of IgE antibodies from the IS instead of IgG.

1. Type I - Immediate or IgE-Mediated
2. Type II - Cytotoxic
3. Type III - Immune-Complex Mediated
4. Type IV - Delayed or Cell-Mediated

An Ag that produces a hypersensitive reaction.

1. The normal process of Ab production: Ag - APC - T_H - B cells - Plasma - Abs.
2. The Abs type is IgE which is unusual. IgE binds mast cells, basophils and eosinophils which produce granules (i.e.histamine)

Because the IgE has been produced and is available as memory cells the reaction is immediate.

Contraction of broncheal cells and vasodilation decreasing BP, PR and RR.

1. Localized
2. Generalized

1. Urticaria (Hives)
2. Allergic Rhinitis (Hay Fever)
3. Asthma (difficulty breathing)

• A systemic effect (often called shock) with a sudden drop in BP, RR, and PR.
• Requires epinephrine to counteract histamine.

Repeated small dose exposure allergy shots designed to produce IgG and "cover" Ag sides before IgE to fight Type I reactions.

• Cells are destroyed by an immune response.
• Abs bind to Ags on the patient's own cell surfaces.
• IgM, IgG, Complement and Bcells bind to Red Blood Cells (RBC) and results in lysis of RBSs.
• Examples are incompatible blood transfusion (ABO) and HDN.

1. Blood Transfusion reaction
2. Rh Blood Group and Hemolytic Disease of the Newborn (HDN).

• Each blood type is defined by an Ag on the the surface of the RBC.
• For every Ag there is a naturally occuring Ab (IgM) in the plasma that is opposite or "anti" of the Ag.
• A to Anti B; B to Anti A; AB to Neither Anti A or B; O (Neither A or B) to Both Anti A and B
• If we transfer blood to the wrong type Abs will to Ag and lysis. Eventually blocking kidneys to failure and death.

• For each ABO blood type there is a Rh blood group positive or negative.
• Rh+ blood types have Rh+ Ags have no naturally occuring Anti Rh+ Ab.
• Rh- blood types have NO Rh- Ags and NO anti Rh- Abs.

• Mother is Rh- and fetus is Rh+

• During first pregnancy the fetus has no problems but transfers at birth and rupture or placenta Rh+ Ags into the Mother's blood.
• The foreign Rh+ Ag stimulates production of specific Ag (IgG) that is a anti-Rh+.
• During the second pregancy, Rh+ fetus recieves anti-Rh+ Abs across the placenta and starts hemolysis of RBCs in fetus.
• Belirubin is released, gondace, and death can occur.

• RhoGAM is given at first pregnancy at 28 weeks and delivery of Rh+ baby.
• RhoGAM is articficial anti-Rh+(IgM)
  • RhoGAM binds to Rh+ Ag that leak in the mother's blood and will prevent the stimulation of the IS to produce naturally occuring anti-Rh+ Abs
• A type of passive artificial immunization.

• Ag-Ab complexes (Immune complexes) initiate several molecular processes including complement activation.
• These complexes are normally eliminated via phagocytosis.
• Some are too small and evade phagocytosis.
• They circulate through blood and become trapped and clog organs, joints and tissues.
• They trigger mast cells to degranulate releasing inflammatory chemicals and damaging tissue.

• Arthus reaction
• Serum sickness

• Localized immediate reaction
• Injection of Ab booster with already high levels of Ab
• At site of injection - inflammation.

• Immediate reaction
• Ab derived from animals given in passive immunization.
• Body reacts to foreign Ab.

• Called Delayed Cell-Mediated 
• Peaks at 2-3 days after exposure to allergin
• Involves APC and Tcells only. No Abs.
• Delay caused by time for APC and T cells to migrate to infection area.

• Tuberculin Skin Test
• Small amount of Ag protein for M. tuberculosis is injected into the skin.
• If person has been exposed/infected or immunized to TB sensitized Tcells release cytokines that damage tissues in area.
• Red thickened are in 48-72 hours indicates prior TB infection and aquired immunity.

• Allergin is poison ivy/oak, jewelry, latex
• Causes swelling and redness
• Produces IR with Tcells which release cytokines with damage tissue.