hypersensitivity and allergy

Question 1

what do hypersensitivity reactions occur against

Answer 1

against harmless foregin antigens, alloantigens (transfusion/graft rejection) and autoantigens (autoimmune disease)

Question 2

types of hypersenstivity

Answer 2

type 1 (immediate)- type 2 (antibody dependent )- type 3 (immune complex mediated)- type 44 (delayed cell mediated)

Question 3

what diseases have type 1

Answer 3

anaphylaxis, asthmas, rhinitis and food allergy

Question 4

mechanism of type 1 hypersensitivty- initial and secondary

Answer 4

1- initial exposure where SENSITISATION (not tolerance) occurs: IgE antibodies produced and bind to IgE rceptors on mast cells/basophils. 2- second exposure where IgE CROSS LINK on mast cells/basophils, causing DEGRANULATION of these cells= release of mediators eg histamines/leukotrienes

Question 5

what diseases have type 2

Answer 5

organ-specific autoimmune diseases eg glomerulonephritis AND autoimmune cytopenias (destrcution of blood cell eg haemolytic anemia)

Question 6

how to test for type 11

Answer 6

immunofluorescence or ELISA for autoantibodies

Question 7

mechanism of type 3 and example

Answer 7

antigen-antibody complexes form in blood vessels and tissues= complement activation= tissue and blood vessel damage eg kidney SLE

Question 8

what diseases have type 4 and TH1 or TH2 mediated

Answer 8

chronic graft rejection, coeliac disease (TH1 mediated), and asthma, rhinitis and eczema (TH2 mediated)

Question 9

mechanism in TH1 mediated type 4- difference cells and cytokines

Answer 9

TH1 cells produce IL2 to activate cytotoxic T cells, produce IFN gamma to activate macrophages which produce TNF, and activate FIBROBLASTS too= fibrosis

Question 10

antibodies involved in type 2/3

Answer 10

IgG

Question 11

genetic risk factors to allergies- important? poly or monogenic + example

Answer 11

important as most allergics have family history- but many genes involved eg of IL4

Question 12

environmental risk factors

Answer 12

age (reduces as you age), gender, family size (more in small families), animals (protects you), diet and infections (protect you)
(GAFIDA)

Question 13

types of inflammation and mediated by what type of hypersensitivty, and what mixed

Answer 13

anaphylaxis, urticaria (itchy rash) and angiodema type 1 mediated: chronic urticaria type 2 mediated, asthma/rhinitsi and eczema MIXED (type 1 and 4)

Question 14

type 4 TH2 mediated- atopic airway disease- mechanism and how eonisophils recruited

Answer 14

sensitisation- TH2 cells cause B cell proliferation= IgE antibodies produced by mast cells. second exposure- TH2 cells cause more IgE production AND recruit eonisophils via IL5

Question 15

importance of neutrophils- in what disease particularly

Answer 15

particularly in asthma

Question 16

mechanism in asthma and how airway narrowed

Answer 16

mast cell activation and degranulation, as well as eonisophil recruitment= histamine/leukotriene release= airway narrowing (VCSM contraction+ mucus secretion)

Question 17

DIAGRAM two phase response in asthma

Answer 17

if given allergen, there is early response (sudden drop in PEF- type 1), then a late response (gradual drop in PEF- type 4)

Question 18

symptoms of asthma

Answer 18

cough, wheezing, mucus production and breathlessness

Question 19

types of allergic rhinitis

Answer 19

seasonal or perennial (year round)

Question 20

symptoms of allergic rhinitis

Answer 20

sneezing, itchy nose/eyes and nasal blockage

Question 21

mild and severe symptoms of food allergy

Answer 21

mild- urticaria/angioedema: severe- diarrhoea, anaphylaxis

Question 22

anaphylaxis- symptoms and corresponding parts of body

Answer 22

severe allergic reaction= swelling of lips (angioedema)ie affects skin, diarrhoea and vomiting ie affects GI, breathlessness, fainting ie affects resp and cardio system

Question 23

diagnosis

Answer 23

skin prick tests (add allergen to skin), total IgE, RAST (add blood to allergen in lab and look at IgE response), and lung function for asthma

Question 24

treatment of anaphylaxis

Answer 24

antihistamines and adrenaline (Epipen)

Question 25

treatment of allergic rhinitis

Answer 25

antihistamines and nasal steroid spray (for nasal blockage)

Question 26

treatment of eczema

Answer 26

steroid cream and EMOLLIENTS

Question 27

treatment of asthma

Answer 27

if mild, used B2 agonist drug: then inhaled steroids and bronchodilators if more severe: then ORAL steroids, SLIT if very severe

Question 28

immunotherapy- what used for and 2 types, and how long it is

Answer 28

for SINGLE antigen hypersensitivities eg pollen- either subcutaenous (SCIT) or sublingual (SLIT)- both 3 years