The document discusses hypersensitivity and its classification. Hypersensitivity refers to an exaggerated or inappropriate immune response that is harmful to the host. It occurs when a sensitized individual is re-exposed to an antigen, leading to tissue damage. Hypersensitivity reactions are classified into four types based on the mechanism and timing of the response: immediate antibody-mediated types I, II and III, and delayed T cell-mediated type IV. Type I involves anaphylaxis, type II involves antibody-dependent cytotoxicity, type III involves immune complex mediated cytotoxicity, and type IV involves delayed type hypersensitivity.

1. HYPERSENSITIVITY
AND ITS CLASSIFICATION
Presented by : Suman Bhattarai
Roll Number : 50 (Fifty)
B.V.Sc & A.H
Agriculture and Forestry University

2. Immune System
Reaction
Damage Protection
Hypersensitivity

3. Hyper-sensitivity :
Greek Word : “Huper” Means over,above and sensitivity
means ability to detect and respond to slight changes
signal
consequence of adaptive immune reaction
Exaggerated reaction or undesired immune
response of immune system ( a.k.a
intolerance )
Results in host damage and other
pathophysiological changes

4. Occurs when already sensitized individual is re-exposed to
same foreign substances
 Essentially has 2 compartments
: 1st dose = Priming or sensitizing dose of antigen
2nd dose = Shocking dose of same antigen that results in
injurious consequences
 Antigen : may be exogenous environmental( dust, drugs,
pollen, food, microbes, chemicals ) and endogenous self type
Both humoral and cell mediated arms of immune response
participates

5. Causes : 1) When Immune system overreacts to
foreign antigens
2) or mechanism of self tolerance fails
 Signs and symptoms
fever, chills, muscle or joint pain, headaches, rales, cough,
chronic bronchitis, shortness of breath, anorexia or weight
loss, fatigue, fibrosis of the lungs, and clubbing of fingers or
toes.
Consequences :
Tissue injury and Death

6.  may be intermediate or delayed type

7. Based on mechanism involved and time taken for reaction,
hypersensitivity classified into
1) Immediate type (Antibody mediated or humoral mediated ) –
type-I,type-II,type-III
2) Delayed type ( T- cell mediated or cell mediated immunity ) –
type-IV
Type –I (Immediate Anaphylaxis )
Type –II (Antibody dependent Cytotoxic hypersensitivity )
Type –III (Immune complex mediated cytotoxicity)
Type –IV (Delayed type hypersensitivity)

8. TYPE – I