ExerciseⅨ Hypersensitivity Test of Guinea Pig
Principle
Hypersensitivity refers to the self tissue injury and/or biological disorder when the sensitized individual contacts the same allergen again.Hypersensitivity is the abnormal or pathologic immune response.According to the mechanisms of hypersensitivity，it could be divided into four types，typeⅠ，Ⅱ，ⅢandⅣ.Type I hypersensitivity is also called immediate type hypersensitivity or anaphylaxis.The antigen leads to hypersensitivity is called allergen.The antibody take part in anaphylaxis is mainly IgE.
In type I hypersensitivity，allergen enters body for the first time and stimulates plasma cells to produce IgE.IgE could bind to the cell surface FcεR of the mast cells or basophils.In this way IgE is produced and attached to these cells surface，which is called allergen-induced period.When the same allergen enters the sensitized body again，allergen could bind to the IgE on the cell surface.Then a series of reaction happen，which lead to the cell activation and biological mediators being released from these cells.These mediators lead to the attack of type I hypersensitivity.This is called allergen-stimulated period.Among these mediators，histamine is the main one that has important biological effects.The rapid release of histamine could increase vascular permeability，lead to vasodilatation，promote smooth muscle contraction and increase secretion of glands.Histamine could lead to the low blood pressure，dyspnea，bellyache，anaphylactic shock，and even death.
Material
1.Adult healthy guinea pig.
2.Fresh egg albumin：take albumin from fresh egg and dilute to the concentration of 1∶10.(https://www.daowen.com)
3.Sterile injector.
Method
1.Allergen-induced injection：2 weeks before test，inject diluted egg albumin 1ml to guinea pig subcutaneously.
2.Allergen-stimulated injection：Immobilize the guinea pig.Find the points of maximal heart impulse and disinfect skin with iodine and ethanol in turn.Give an intracardiac injection of 1 ml diluted egg albumin.Release the guinea pig and observe its response.
Result
In a few minutes after the allergen-stimulated injection，a series of symptoms appear in the guinea pig.Symptoms include excitement，scratching nose，dyspnea，hair standing，convulsion，jumping and even death.