Dr Elsa van Duuren FCPSA May 2012 - · PDF fileDr Elsa van Duuren ... Diagnosis made on...

Dr Elsa van Duuren

FCPSA

May 2012

The adaptive immune system produces antibodies in reaction to antigenic stimuli

We continually produce antibodies against self molecules

IgM,

Weak avidity molecules that cross react with multiple antigens

Autoimmune disease:

Pathogenic autoantibodies produced

High avidity IgG bind specific antigens

Form immune complexes

Defective immune complex clearing

Defective regulation of Ig formation

Persistance

Systemic autoimmune diseases

Widespread deposition of immune complexes and subsequent inflammatory processes

Systemic Lupus Erythematosus

Antiphospholipid antibody syndrome

Scleroderma

Polymyositis/ dermatomyositis

Sjögren syndrome

Mixed connective tissue disease

Rheumatoid arthritis

Vasculitidies

There are no single characteristic features

Common clinical features

Diagnostic or classification criteria

ACR criteria (American Center of Rheumatology, former American Rheumatism Association, ARA)

European criteria

Criteria of single authors/author groups

Prevalence: Percentage of patients in the population

Incidence: New patients per 100,000 population and per year

Disease Prevalence Incidence

Rheumatoid Arthritis 1-3% ca. 30

SLE 0.04-0.05% 6-8

Scleroderma - 0.3-0.4

Polymyositis/Dermatomyositis - 0.2-0.5

Sjögren‘s Syndrome 0.3-1% -

Serological tests are used to further evaluate a patient with a clinical picture of a connective tissue disease

To confirm a specific diagnosis

To guide appropriate management

Assess disease activity (seldom)

Sensitivity

Specificity

Positive or negative predictive value

The likelihood that a patient with a particular clinical picture will have a positive serologic test result

A specific test is more likely to identify a patient with a disease and exclude someone without the disease

A test with a high specificity can rule in/ not rule out a disease

A positive test result provides additional confirmation that the disease is present

Proportion of patients that will test positive or negative who do or do not have the disease

ANA (antinuclear ANTIBODIES)

general name for all autoantibodies which react with nuclear antigens

ANA, anti dsDNA, centromere proteins and histones

ENA (extractable nuclear ANTIGENS)

can be eluted by salt extraction

Sm, U1-snRNP, Ro/SS-A, La/SS-B, Jo-1, Scl-70, PM-1, Mi-2 and Ku

The most popular screening test for ANA is the indirect immunofluorescence assay (IFA) using HEp-2 cells as substrate.

•Detects all ANA with high sensitivity (except for e.g. Ro, Jo1 and Rib-P antibodies).

•Results shown in a certain pattern.

•Staining pattern lacks specificity due to overlap between patterns and diseases

•More specific antibody tests have overtaken staining pattern

A Homogeneous

B Coarse speckled

C Polymorphic

D Centromere

E Multiple nuclear dots

F Nucleolar

G Fine speckled

H Cytoplasm, fine speckled

I Cytoplasm, fine speckled to homogeneous

Pattern target antigen disease association A homogeneous dsDNA SLE

Histones drug-induced SLE

B coarse speckled U1RNP MCTD Sm SLE

C polymorphic PCNA SLE

D centromere CENP CREST, SSc

F nucleolar PM-Scl SSc, PM, Overlap Fibrillarin SSc RNA-Pol III SSc

G fine speckled Ro/SS-A SS, SLE La/SS-B SS, SLE Scl-70 SSc Mi-2 DM

H, I cytoplasm Jo-1 PM/DM Rib-P SLE SRP PM/DM

an

d m

ore ?

Even high titres (1:640) have only a positive predictive value of 35% for connective tissue diseases (CTDs).

ANA in IFA have a predictive value of 11% for SLE and 11% for other CTDs.

4 of 5 ANA positive results cannot be traced back to antigens with known clinical relevance.

IFA results have only a limited clinical usefulness for the doctors

Various autoimmune diseases Connective tissue diseases (CTD) Autoimmune hepatitis Primary biliary cirrhosis Rheumatoid arthritis Addison’s disease Hashimoto thyroiditis Type 1 diabetes mellitus

Non-autoimmune diseases Cancer Gastrointestinal diseases Lung diseases Skin diseases Infections

• ANA are not very specific for certain diseases

• Mainly used to support diagnosis of CTDs

•Healthy population:

• titre 1:40 32%

• titre 1:80 13%

• titre 1:160 5%

• Antibodies directed against small ribonuclear proteins that play a role in mRNA splicing

• Highly specific

• Appropriate to test for in a patient:

• ANA positive + features of a specific CTD

• ANA negative + known CTD

• For diagnostic confirmation

• Do not exclude a specific CTD

• Do not correlate with disease activity and may be found in patients without active disease

• Skin and mucous membranes • Synovium (joints) • Serosal membranes • Kidneys • Central nervous system • Lungs • Heart • Hematopoietic system • Constitutional symptoms:

• Fever, Fatigue, weight loss

Any part of the skin can be involved:

Epidermis

Dermis

Sub-dermal fat

Nailfold capillary

Inflammation

Infarction

Diffuse

Localised

Central nervous system Epilepsy Hemiparesis Cranial nerve lesions Brain stem/ cord lesions Aseptic meningitis Transverse myelitis

Peripheral nervous system Peripheral neuropathies Myasthenia gravis Mononeuritis multiplex

Psychiatric Disorders of mental function

1. Malar rash

2. Discoid rash

3. Photosensitivity

4. Oral ulcers

5. Arthritis

6. Serositis

7. Renal disorder

8. Neurologic

disorder

9. Hematologic

disorder

10. Immunologic

disorder

11. Antinuclear

Antibody

Updating the American College of Rheumatology revised criteria for the classification of

systemic lupus erythematosus, Hochberg MC, Arthritis Rheum 1997, 40: 1725

a) Anti-dsDNA

or

b) Anti-Sm

or

c) Positive finding of

antiphospholipid antibodies

based on:

1. An abnormal serum level of

IgG or IgM anticardiolipin

antibodies

or

2. A positive test result for

lupus anticoagluant using a

standard method

or

3. A false positive serologic

test for syphilis, known to be

positive for at least 6 months

Any of four or more

criteria should be

present, serially or

simultaneously.

> 4 criteria positive: 96

% SLE

• Usually seen in women of childbearing age with: • Constitutional symptoms of fever, weight loss,

malaise, and severe fatigue

• Skin rash and/or stomatitis

• Arthritis

• Renal disease

• Cytopenias

• Although 90% of patients are female, SLE can be seen at any age in either sex

• ANA

• Abnormal titer >1:160

• Clinically significant

• High sensitivity: 93%

• Seen in 95% of SLE

• Not specific for SLE

• Specificity 57%

• Anti-ds DNA

• Seen in 60% of patients with SLE

• Highly specific for SLE

• Low titer rarely seen in other inflammatory conditions

• Strongest clinical association is with nephritis

• Anti-Sm antibodies

• Seen in 10% to 30% of SLE patients

• Highly specific for SLE

Antigen: Phosphoproteins P0 (38 kDa), P1 (19 kDa) and P2 (17 kDa) of the 60S subunit of the ribosomal complex.

Possibly linked to neuropsychiatric manifestations and liver manifestatinos

Highly specific for SLE

SLE 10-20%

Antigens: Histones plus DNA plus other DNA-binding proteins

Is said to be specific for SLE, but data are controversial (question of belief)

Doubtful clinical relevance

Disease Antibody Prevalence

SLE dsDNA

Sm

Rib-P

PCNA

Other:

Phospholipid

Ro/SS-A

La/SS-B

U1-snRNP

C1q

Histone

50-80 % (ACR criterion)

5-30 % (ACR criterion)

10-20 %

2-10 %

40-60 % (SLE with secondary Antiphospholipid

syndrome)

25-60 % (neonatal LE, SLE with limited organ

involvement, SCLE)

19-30 % (SLE with limited organ involvement, SCLE)

13-32 %

Antihistone antibody test:

Sensitive, but non-specific

Positive in 95% of patients with drug induced SLE

Negative result makes drug induced SLE less likely

Also positive in 50% patients with SLE

Most patients asymptomatic

To make diagnosis:

Drug use

High titer ANA, antihistone ab

Negative dsDNA ab

Clinical picture of SLE

Can occur as a primary syndrome or secondary to SLE

Highly variable clinical picture

From benign to the catastrophic antiphospholipid syndrome

Clinical picture due to recurrent venous or arterial thrombosis

Diagnosis made on clinical and serological picture Vascular thrombosis: one or more episode of

Arterial thrombosis

Venous thrombosis

Small vessel thrombosis in any tissue or organ

Pregnancy loss: one or more unexplained deaths of normal foetus at or after 10 weeks

Prem birth before 34 weeks Severe preeeclampsia, eclampsia, or placental

insufficiency

3 or more unexplained consecutive miscarriages

Anticardiolipin antibody (aCL)

IgG and/or IgM in medium or high titer

2 tests 6 weeks apart

AND: Measured by a standardised ELISA for ß2 glycoprotein-1 dependent anticardiolipin

antibody

Abnormality present in plasma at least 2 occasions 6

weeks apart

Autoimmune disease of exocrine glands

Decreased exocrine secretions: Eyes

Mouth

Systemic disease Lungs

Renal

GIT

Skin

Polyarthritis

Primary or secondary

Immunologic alterations in peripheral blood

Relative T-cell lymphopaenia

Increased circulating B-cells

75% SS-A

40% SS-B

60% ANF or RF positive

Polyclonal hypergammaglobulinaemia

IgA has immunopathogenic role in SS

Symptoms of dry eyes Daily persistent, troublesome dry eyes >3mo

Recurrent sensation of sand/gravel in eyes

Use of tear substitutes

Oral symptoms Daily feeling of dry mouth >3 mo

Recurrent or persistent swollen glands

Frequently drink fluid to swallow food

Ocular signs Objective signs of dry eyes:

Schirmer’s test 5mm in 5 mins

Rose Bengal dry eye score

Histopathology Focus score 1

Salivary gland involvement Objective evidence of gland involvement

Unstimulated salivary flow 1.5 ml in 15 mins

Parotic sialography showing presence of sialectasis, without evidence of obstruction of major ducts

Salivary scintigraphy showing delayed uptake, reduced concentration, delayed excretion of tracer

Autoantibodies SS-A or SS-B antibodies

Disorder of connective tissue characterised by degenerative and inflammatory changes that subsequently lead to intense fibrosis

Localised

Generalised

Changes in the blood vessels

Concentric proliferation

Thickening of intima and basement membrane

Organ involvement

Skin

Gastro-intestinal tract

Kidneys

Lungs

ANA Sensitivity: 85%, Specificity 54%

Antibodies against Scl-70 Sensitivity 12%, Specificity 100%

Other ENAs CENP

Fibrillarin

RNA Polymerase III

Calcinosis cutis

Raynaud’s phenomenon

Esophageal dysmotility

Sclerodactyly

Telangiectasis

Defining criteria:

Symmetrical progressive proximal muscle weakness

Muscle biopsy showing inflammatory changes

Elevated muscle enzymes

Electromyographic abnormalities

Characteristic dermatological changes

Progressive proximal weakness

Insidious onset

Intense morning stiffness and pain

Heliotrope rash

Goddron’s patches

ANA can be positive, but not diagnostic

Antibodies against cytoplasmic aminoacyl tRNS synthetase (ARS)

Jo-1:

20% of patients

Mi-2

9% of myositis patients

20% DM patients

Overlap syndrome with features of scleroderma, RA, SLE, and PM/DM

AND characteristic high titre of U1-snRNP antibodies.

First symptoms: Raynaud‘s phenomenon (often many years in advance)

Muscle weakness

Swollen hands and general swelling of the skin

Synovitis

At least 50 % of patients develop a classical connective tissue disease in the course of 10 years

Group of diseases characterised by inflammatory infiltration of blood vessels

• Multisystem inflammatory disease

• Rapidly progressive major organ dysfunction

• Constitutional symptoms (fever, weight loss)

• High ESR, severe anemia, thrombocytosis

• Evidence of small-vessel inflammation: • In the kidneys = active urinary sediment • In the lungs = hemoptysis, dyspnea • In the skin = palpable purpura/hemorrhage

• Acute neurologic changes • Footdrop • Altered mental status

• Tests suggesting immune complex formation and/or deposition • Rheumatoid factor and cryoglobulins

• Antinuclear antibodies (ANA)

• Low C3 or C4 levels

• Tests suggesting necrotizing vasculitis without immune complex deposition • Antineutrophil cytoplasmic antibodies (ANCA)

• Tests suggesting systemic inflammation • Erythrocyte sedimentation rate (ESR)

• C-reactive protein (CRP)

• ANCA by ELISA methods

• Proteinase 3 (PR3)

• Myeloperoxidase (MPO) = MPA

• ANCA by immunofluorescence methods

• c-ANCA:

• Wegener’s disease: 60% to 90%

• p-ANCA

• Microscopic polyangiitis (MPA) : 50% to 80%

• UC : 40% to 80%

• Crohn’s: 10% to 40%

Hoffman GS. Arth Rheum. 1998;41(a):1521–1537.

• Consider tissue biopsy of affected organ to determine

• Vessel size

• Histologic features of vessel inflammation

Vessel wall necrosis

Granulomas/giant cells

Immune complex and/or C3 deposition

• Consider angiography of mesenteric or cerebral vessels as clinically indicated

Vasculitis Vasculopathy

• Infectious diseases

• Bacterial endocarditis

• HIV infections

• Viral hepatitis

• Paraneoplastic syndromes

• Atrial myxoma

• Cholesterol emboli syndrome

• Toxic drug effects

• Ergots

• Cocaine

• Amphetamines

Presence of a heart murmur

Necrosis of lower extremity digits

Splinter hemorrhages

Prominent liver dysfunction

History of recreational drug use

History of high-risk sexual activity

Prior diagnosis of neoplastic disease

Unusually high fevers

The diagnosis of a CTD remains clinical

History

Physical examination

Serologic testing as a diagnostic and disease management tool needs to be

Properly applied

Properly interpreted