1. HYPERSENSITIVITY DACIL & HARVI

2. What are the Two Types of Immune System? 1. INNATE  HOURS ◦ Epithelial Barriers ◦ Phagocytes ◦ Dendritic Cells ◦ Complement ◦ Natural Killer Cells 2. ADAPTIVE  DAYS/MONTHS ◦ B-Lymphocytes  ANTIBODIES ◦ T-Lymphocytes  Effector T Cells APPs

3. What is meant by the term HYPERSENSITIVITY? ◦ An INAPPROPRIATE and EXCESSIVE immunological reaction to an external antigen. ◦ The external antigen is usually called an ALLERGEN!

4. What is meant by the term Autoimmunity? ◦ INAPPROPRIATE and EXCESSIVE immunological reaction to a self- antigen/auto-antigen ◦ Due to a dysfunctional control of the immune system.

5. TYPES OF HYPERSENSITIVITY REACTIONS TypeNameMediatorsExamples IImmediate or IgE mediated A llergic IgE + Mast cells A llergies Anaphylaxis Asthma Atopy- genetic predisposition IIAntibody-dependent C ytotoxic IgM/ IgGAutoimmune haemolytic anaemia- G oodpasture’s syndrome- lung + kidney Myasthenia Gravis G rave’s disease IIIImmune complex I mmune complex deposition IC S erum Sickness Extrinsic Allergic Alveolitis (EAA) Rheumatoid Arthritis S ystemic Lupus Erythematosus IVDelayed or Cell mediated D elayed T lymphocytesAllergic Contact Dermatitis Chronic Transplant Rejection MS T uberculin Skin Test AnGST

6. Type 1- Immediate/ IgE mediated

7. What is the process of type I? 1.Sensitisation occurs first (IgE production & binding to mast cells) 2. Thereafter exposure generates immediate response (degranulation) Angioedema Urtricaria- rash caused by fluid leaking out of surface blood vessels. Hives/ wheals

8. A 5 year old child is being brought to your dept after developing noisy breathing and a rash. He has respiratrory distress with a RR 50, Sats of 90% on high flow oxygen. Pulse is 140. CRT of 4 secs. The child is accompanied by his mother. He is having a nebuliser on route. The mother says she took her child to the GP this morning who prescribed some antibiotics. She gave these about half an hour ago. Within in a few minutes he became wheezy and complained of difficulty in breathing. He is not known to be allergic to anything. ◦ What is your immediate plan of action? ◦ ABCDE ◦ Lie patient down ◦ IV fluids When performing your examination you notice the patient is pale, sweaty and has a generalised urtricarial rash, swelling around lips and eyes, and pyrexial at 38.2c ◦ What is your diagnosis? ◦ Anaphylaxis ◦ What will you now give? ◦ Adrenaline ◦ IV chlorphenamine ◦ IV hydrocortisone ◦ Nebulised salbultamol ◦ The child does not appear to improve over the next 5 minutes, what should you do? ◦ Repeat adrenaline ◦ How is adrenaline given? ◦ 500mcg IM

9. Tom’s girlfriend buys him a stylish watch for his birthday which he immediately puts on. Later, when she leaves he decides he doesn’t like it so decides not to wear it. However, a couple of days later she notices him not wearing it, so he decides to put it on. However, to his dismay Tomnotices the skin underneath the watch is becoming itchy and red, by the afternoon there are vesicles present. ◦ What is the diagnosis? ◦ Allergic contact dermatitis ◦ What kind of hypersensitivity reaction is this? ◦ Type IV (delayed/ cell mediated) ◦ What distinguishes this type of reaction to a Type I? ◦ Slower and more specific/ localised ◦ To prove its type I can measure blood markers (IgE) ◦ How would the GP identify the exact allergen? ◦ Skin patch testing ◦ What would be the first line of treatment for Tom? ◦ Avoidance ◦ Metals e.g. nickel ◦ What other treatments are possible? ◦ Anti-histamines- Topical Eye drops or Systemic Tablets ◦ Steroids- Topical Eye drops or Systemic Tablets ◦ Desensitisation- Allergen immunotherpay ◦ Creates tolerances to allergens by small exposure gradually increasing sublingually or subcutaneously.

10. THE END- THANKOOOO