Autoimmune and Autoinflammatory Diseases 3

Question 1

What are antinuclear antibodies?

Answer 1

Group of antibodies that bind to nuclear proteins
Test by staining of Hep-2 cells (human epidermoid cancer line)
Very common
Low titre antibodies (<1:80) often found in normal individuals (esp older women)

Question 2

What may a person with SLE present with?

Answer 2

history of fatigue
Generalised arthralgia, particularly of small joints of hands
Hair fall
Mouth ulcers
Butterfly rash

Question 3

What is the genetic predisposition of SLE?

Answer 3

Abnormalities in clearance of apoptotic cells
Polymyorphisms in genes encoding complement, MBL, CRP

Abnormalities in cellular activation
Polymorphisms in genes encoding/controlling expression of cytokines, chemokines, co-stimulatory molecules, intracellular signalling molecules

B cell hyperactivity and loss of tolerance

Antibodies directed particularly at intracellular proteins
? Debris from apoptotic cells that have not been cleared
Nuclear antigens - DNA, histones, snRNP
Cytoplasmic antigens - Ribosome, scRNP

Question 4

What is the pathophysiology of SLE?

Answer 4

Antibodies bind to antigen to form immune complexes

Immune complexes deposit in tissues
Skin, joints, kidney

Immune complexes activate complement (classical pathway)

Immune complexes stimulate cells expressing Fc and complement receptors

Question 5

How can you compare the disease pathology in Type II and Type III?

Answer 5

Immune complexes deposit in basement membrane in a type III response
Note the contrast in staining pattern compared with a type II response where antibody specific for the basement membrane (rather than immune complexes) despoit.

Question 6

How do you measure antibody levels?

Answer 6

Measured by titre (the minimal dilution at which the antibody can be detected) or by concentration in standardised units

Question 7

What are the targets of ANA?

Answer 7

A positive ANA result will trigger the laboratory to investigate for dsDNA and ENA antibodies

dsDNA

Ro, La, Sm, U1RNP Ribonucleoproteins

SCL70
Topoisomerase

Centromere

Question 8

What is the pattern for ANA in SLE?

Answer 8

Homogeneous staining associated with specificity for dsDNA
Specificity investigated with ELISA based assay

Question 9

What are anti dsDNA antibodies used for?

Answer 9

Measures antibodies against double stranded DNA
Are highly specific for SLE (95%)
Occur in ~60-70% of SLE patients at some time in their disease
Very high titres are often associated with more severe disease, including renal or central nervous system involvement.
Useful in disease monitoring
an increase in antibody titre is associated with disease activity and may precede disease relapse.
False positive results unusual (<3%)

Question 10

What is speckled antibody?

Answer 10

Associated with antibodies to extractable nuclear antigens
Specificity is for some ribonucleoproteins (Ro, La, Sm, U1RNP) – confirm with ELISA

Question 11

What are anti ENA antibodies?

Answer 11

Ro, La, Sm, RNP (all are ribonucleoproteins)
Antibodies may occur in SLE
Anti-Ro and La are also characteristically found in Sjogren’s syndrome
Titres not helpful in monitoring disease activity

Question 12

What is classical pathway of complement?

Answer 12

Formation of antibody-antigen immune complexes
activate complement cascade via classical pathway
complement components become depleted if constantly consumed

Quantitation of C3 and C4 acts as a surrogate marker of disease activity

[NB we measure UNACTIVATED complement proteins, not activated forms]

Question 13

What is the complement profile in SLE?

Answer 13

Question 14

What is APLS?

Answer 14

•Anti-phospholipid syndrome

–Recurrent venous or arterial thrombosis

–Recurrent miscarriage

–May be associated with livedo reticularis, cardiac valve disease

–May occur alone (primary) or in conjunction with autoimmune disease (secondary)

Question 15

What are the antibody tests for APLS?

Answer 15

•Three antibody tests

–Lupus anti-coagulant

• Prolongation of phospholipid-dependent coagulation tests
• cannot be assessed if the patient is on anticoagulant therapy

–Anti-cardiolipin antibody

•Antibody specific for negatively charged phospholipids

–Anti-B2 glycoprotein 1 antibody

•Antibody specific for glycoprotein found associated with negatively charged phospholipids

Check all three antibodies in individuals presenting with unexplained thrombosis or recurrent pregnancy loss

Question 16

What is CREST?

Answer 16

•Limited Cutaneous Systemic Sclerosis (CREST)

Skin involvement does not progress beyond forearms

(although it may involve peri-oral skin)

–Calcinosis

–Raynauds

–Oesophageal dysmotility

–Sclerodactyly

–Telangectasia

–

–Primary pulmonary hypertension

Question 17

What is Diffuse Cutaneous Systemic Sclerosis?

Answer 17

•Diffuse Cutaneous Systemic Sclerosis

Skin involvement does progress beyond forearms

• CREST features
• More extensive gastrointestinal disease
• Interstitial pulmonary disease
• Scleroderma kidney / renal crisis

Question 18

What is the difference between limited (CREST) and diffuse systemic sclerosis?

Answer 18

Limited:

Anti-centromere antibodies

Diffuse:

Nucleolar pattern

Anti-topoisomerase antibodies (Scl70)

RNA polymerase

Fibrillarin

Question 19

What is the difference between dermatomyositis and polymositis?

Answer 19

Dermatomyositis

• Muscle Bx: perivascular CD4 T cells and B cells
• Immune complex mediated vasculitis

Polymositis

• Muscle Bx: CD8 T cells surround HLA Class I expressing myofibres
• CD8 T cells kill myofibres via perforin / granzymes

Question 20

What are the Ix for myositises?

Answer 20

•Positive ANA (in some patients)

– extended myositis panel - Anti Jo-1 positive, Anti-Mi2, Anti-signal recognition peptide antibody

(Extra info)

Anti-aminoacyl transfer RNA synthetase antibody eg Jo-1 (cytoplasmic)

Anti-signal recognition peptide antibody (nuclear and cytoplasmic) (PM)

Anti-Mi2 (nuclear) (DM>PM)

Question 21

What are investigations for CTDs?

Answer 21

Question 22

What are the autoantibodies for rheumatological diseases?

Answer 22

Question 23

What are the systemic vasculitides?

Answer 23

Question 24

What are the 3 types of ANCA associated SV vasculitis?

Answer 24

Microscopic polyangiitis / Microscopic polyarteritis / MPA

Granulomatosis with polyangiitis / Wegener’s granulomatosis / GPA

Eosinophilic granulomatosis with polyangiitis / Churg-Strauss syndrome / eGPA

Question 25

What are ANCA?

Answer 25

Antibodies specific for antigens located in primary granules within cytoplasm of neutrophils

Inflammation may lead to expression of these antigens on cell surface of neutrophils

Antibody engagement with cell surface antigens may lead to neutrophil activation (type II hypersensitivity)

Activated neutrophils interact with endothelial cells causing damage to vessels - vasculitis

Question 26

What is cANCA?

Answer 26

–Cytoplasmic fluorescence

–Associated with antibodies to enzyme proteinase 3

–Occurs in > 90% of patients with granulomatous polyangiitis with renal involvement

Question 27

What is pANCA?

Answer 27

Perinuclear staining pattern

Associated with antibodies to myeloperoxidase

Less sensitive and specific than cANCA

Associated with microscopic polyangiitis and eosinophilic granulomatous polyangiitis

Question 28

Investigations show:

Positive antinuclear antibodies (ANA)

Anti-dsDNA+ve

Low C3 and C4

High ESR

Negative results for:

Ro, La, Sm, RNP

SCL70

Centromere

Jo-1

Anti-neutrophil cytoplasmic antibodies (ANCA)

What is the diagnosis?

Systemic sclerosis

Systemic lupus erythematosus

Dermatomyositis

Sjogrens syndrome

ANCA associated vasculitis

Answer 28

SLE

Question 29

Investigations show:

Positive anti-neutrophil cytoplasmic antibodies

(ANCA)

Negative results for:

Anti-nuclear antibody (ANA)

Normal complement

Raised ESR and CRP

What is the diagnosis?

Systemic sclerosis

Systemic lupus erythematosus

Dermatomyositis

Sjogrens syndrome

ANCA associated vasculitis

Answer 29

ANCA associated vasculitis