DIAGNOSIS OF AUTOIMMUNE DISEASES

Question 1

Recognise some examples of autoinflammatory diseases

Answer 1

These conditions include familial Mediterranean fever (FMF), cryopyrin associated periodic syndrome (CAPS), hyperimmunoglobulinemia D syndrome (HIDS), TNF receptor-associated periodic syndrome (TRAPS), and several other chronic diseases that have recurring fevers and inflammation as the main symptoms.

Question 2

Autoinflammatory

Answer 2

= Malfunction in the Innate Immune System

Question 3

Autoimmune

Answer 3

Malfunction in the Adaptive Immune System

Question 4

Recognise the common characteristics of autoimmune disease

Answer 4

Fatigue, Fever, General ill-feeling (malaise), Joint pain and Rash

Question 5

diagnostic tests and techniques used investigation of autoimmune diseases

Answer 5

Non-specific: Inflammatory markers e.g. Complement, albumin, ESR, CRP, ferritin, Fibrinogen, Haptoglobin
Disease specific: Autoantibody testing and HLA typing

Question 6

Rheumatoid factor

Answer 6

Antibody (IgM, IgG or IgA) directed against the Fc portion of IgG. Commonly found in rheumatoid arthritis but not diagnostic of the diseases (sensitivity and specificity around 70%). Can be seen with other diseases in which polyclonal stimulation of B cells is seen (chronic infections). High titters may be pathogenic in vasculitis.

Question 7

ANTI NUCLEAR ANTIBODIES: origins of ANA

Answer 7

Anti-CCP more specific (see previous lecture).
• Positive ANCA is extremely useful in suggesting the diagnosis in the proper clinical setting
• Histopathology remains the gold standard for diagnosis in most cases
• Negative ANCA assays do not exclude AASV since 10%-50% of patients may be ANCA neg
• Persistence of ANCA in the absence of clinical indications of active disease does not indicate a need for continued treatment
• Reemergence of ANCA pos in a patient who was ANCA neg whilst in remission suggests a risk of disease flare. The temporal correlation between the return of ANCA and a disease flare is poor

Question 8

Organ specific autoimmune diseases

Answer 8

• Anti-mitochondrial Ab specific for primary biliary sclerosis
• Anti-smooth muscle and anti-liver/kidney/microsomal (LKS) Abs, found in autoimmune hepatitis
• Antibodies detected by IF screening using rodent tissue block (oesophagus, liver and kidney) and antigen specific ELISA

Question 9

Autoantibodies in Type I DM

Non-pathogenic

Answer 9

Several types: islet cell antibodies, anti-GAD65  anti-GAD67, anti-insulinoma antigen 2 (IA-2)			
Insulin autoantibodies (IAAs). Disappear with progression of disease and total destruction of β islet cells.