A clinical overview of autoimmune disease

Question 1

What is autoimmunity?

Answer 1

T cells with high affinity for self antigens should be removed by negative selection in the thymus
Some T cells will escape - these are CD4+ cells (checkpoint 1)
APC present on MHC I
Some CD4+ cells recognise this antigen and mount immune response (autoimmunity)
Checkpoint 2: Treg cells stimulate CD4+ to apoptosis and dampen immune response
If no Treg cells, DC presents self-antigen to CD4+ cell
For CD4+ to be activated, needs interaction between CD80 on DC and CD28 on CD4+
CD80 upregulated on inflammation

Question 2

Autoimmune diseases in childhood

Answer 2

T1DM, Rheumatic fever, Kawaski’s disease

Question 3

Risk factors for autoimmune disease

Answer 3

Family history
Genetics - HLA DR2 (narcolepsy and Goodpasture’s and MS), HLA DR3 (myasthenia graves, Hashimoto’s), HLA DR4 (RA and SLE)
Drugs increase SLE risk and smoking increases RA risk

Question 4

What is elevated in gut inflammation?

Answer 4

Calprotectin

Question 5

How to differentiate between UC and Crohn’s?

Answer 5

UC has bloody diarrhoea and only affects the mucosal wall of the colon in a continuous fashion
Crohn’s affects the whole GIT, affects all layers, causes vaginal involvement, granulomas, abscesses etc

Question 6

Treatment for UC and Crohn’s

Answer 6

Steroids
Elemental diet 
Anti-TNF (infliximab)
5-ASA drugs (mesalazine)
DMARDs (methotrexate)

Question 7

Sx Grave’s

Answer 7

Hypothyroidism, non-tender goitre, proptosis

Question 8

Risk factors Grave’s

Answer 8

Age 30-50, pregnancy, smoking

Question 9

Tests Grave’s

Answer 9

Anti-TSH ABs

Question 10

Treatment Grave’s

Answer 10

Anti-thyroid drugs (carbimazole), radiodiodine and thyroidectomy

Question 11

Sx Coeliac’s

Answer 11

Cramps and diarrhoea

Question 12

ABs coeliac’s

Answer 12

Anto-TTG, IgA subtype

Question 13

Treatment Coeliac’s

Answer 13

Avoid gluten, steroids, imunosuppressants

Question 14

Where is IgA found?

Answer 14

Secretions (saliva, tears, breast milk)

Question 15

IgA diseases

Answer 15

IgA nephropathy, HSP, coeliacs

Question 16

When is IgE made?

Answer 16

parasitic infections

Allergy, atrophy, anaphylaxis

Question 17

When will IgM be made?

Answer 17

Acute infection - diagnoses acute vs chronic infection

Question 18

Sx RA

Answer 18

Symmetrical small joint swelling and redness
Worse in morning
Swan neck deformity 
Ulnar deviation 
Boutonniere deformity

Question 19

Tests for RA

Answer 19

Rheumatoid factor (sensitive, not specific) and anti-CCP (specific, not sensitive)

Question 20

Treatments RA

Answer 20

Steroids, DMARDs (methotrexate, leflunomide), infliximab

Question 21

Sx Addison’s

Answer 21

Low sodium, high potassium ,low BP, pigmentation

Question 22

Why do you get pigmentation with Addison’s

Answer 22

No cortisol means no neg feedback - more ACTH made (formed by cleaving of POMC to ACTH and MSH) and more melanin made

Question 23

Short synACTH test

Answer 23

SynACTH given
Monitor at baseline, 30 min and 60 min
Cortisol should double
If not, indicated adrenal insufficiency

Question 24

Tx Addison’s

Answer 24

Hydrocortisone and fluid/glucose management