different types of hypersensitivities
TYPE 1: IMMEDIATE
TYPE 2: ANTIBODY MEDIATED
Feature
Known as anaphylactic HS
Fast response (minutes)
Disorders/
Reactions
Athopy
Clinical manifestation includes asthma, eczema, hay fever, food allergy
Has family history with similar condition
Show immediate wheal and flare skin reaction to allergen
Strong hereditary linkage seen in human
Autoimmune haemolytic anaemia
Spontaneous/ induced by drugs
Reacts to blood group Ag – produce Ab to self RBC
Test: direct antiglobulin test
Anaphylaxis
Systemic mediated
Edema in tissue, fall BP(secondary to vasodilation)
Cause by:
Ag from injection present in blood
Insect sting
Absorption across epithelium surface i.e. skin, GUT
Allergen → activates mast cell → release of mediators → gain access to vascular beds in body
Haemolytic disease of the new born (HDNB)
Mother sensitizes to Ag (Rhesus D) of infant’s RBC & make IgG to the Ag
Ab cross placenta → react with fetal RBC → destruction of RBC
Risk arises when,
Rh+-sensitized Rh- mother carries second Rh+ infant(1st pregnancy)
Fetal RBC leak back across placenta into maternal circulation & recognized by maternal immune system
Affect subsequent children
Test: direct antiglobulin test
Asthma
Inflammatory disease
Cause by repeated immediate hypersensitivity & late phase reaction in lung
Leads to:
Chronic bronchial inflammation with eosinophil
Bronchial smooth cell hypertrophy
Bronchial smooth cell hyper reactivity to bonchoconstrictor
Coexist with bronchitis/emphysema
Good posture’s syndrome
Autoantibody (IgG) to glomerular BM
Myasthenia gravis
IgG to Ach receptor → reduce availability of Ach at motor end plate
Pemphigus
IgG to intracellular adhesion molecule → form junction between epidermis → disrupt cellular adhesion → epidermis breakdown
Incompatible blood transfusion
Recipient sensitizes to donor’s RBC Ag surface
Thrombocytopenia, erythroblastosis fetalis
Pathologic immune mechanism
TYPE 2: ANTIBODY MEDIATED
Feature
Known as anaphylactic HS
Fast response (minutes)
Disorders/
Reactions
Athopy
Clinical manifestation includes asthma, eczema, hay fever, food allergy
Has family history with similar condition
Show immediate wheal and flare skin reaction to allergen
Strong hereditary linkage seen in human
Autoimmune haemolytic anaemia
Spontaneous/ induced by drugs
Reacts to blood group Ag – produce Ab to self RBC
Test: direct antiglobulin test
Anaphylaxis
Systemic mediated
Edema in tissue, fall BP(secondary to vasodilation)
Cause by:
Ag from injection present in blood
Insect sting
Absorption across epithelium surface i.e. skin, GUT
Allergen → activates mast cell → release of mediators → gain access to vascular beds in body
Haemolytic disease of the new born (HDNB)
Mother sensitizes to Ag (Rhesus D) of infant’s RBC & make IgG to the Ag
Ab cross placenta → react with fetal RBC → destruction of RBC
Risk arises when,
Rh+-sensitized Rh- mother carries second Rh+ infant(1st pregnancy)
Fetal RBC leak back across placenta into maternal circulation & recognized by maternal immune system
Affect subsequent children
Test: direct antiglobulin test
Asthma
Inflammatory disease
Cause by repeated immediate hypersensitivity & late phase reaction in lung
Leads to:
Chronic bronchial inflammation with eosinophil
Bronchial smooth cell hypertrophy
Bronchial smooth cell hyper reactivity to bonchoconstrictor
Coexist with bronchitis/emphysema
Good posture’s syndrome
Autoantibody (IgG) to glomerular BM
Myasthenia gravis
IgG to Ach receptor → reduce availability of Ach at motor end plate
Pemphigus
IgG to intracellular adhesion molecule → form junction between epidermis → disrupt cellular adhesion → epidermis breakdown
Incompatible blood transfusion
Recipient sensitizes to donor’s RBC Ag surface
Thrombocytopenia, erythroblastosis fetalis
Pathologic immune mechanism