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Dermatology Board Prep > DERM (17) Rheumatologic Dermatology > Autoantibodies encountered in patients with autoimmune connective tissue diseases > Flashcards

Autoantibodies encountered in patients with autoimmune connective tissue diseases Flashcards

1
Q

What does the ANA test for?

A

Tests for a group of Anti-nuclear antibodies commonly defined as autoantibodies that target primarily nuclear components including DNA, small nuclear ribonucleoproteins (snRNP) and are detected by the fluorescent antinuclear antibody test

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2
Q

What diseases are increased ANA titers seen in ?

A

Systemic lupus erythematosus, systemic sclerosis, and dermatomyositis

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3
Q

Pathogenic potential of ANA antibodies?

A

These reflect basic inflammatory events in tissue but rarely care pathogenic potential

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4
Q

Fluorescent antinuclear antibody (FANA) vs ELISA test?

A

Elisa is less expensive, more convenient, but has increased density and decreased specificity.

The FANA can also give you titers

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5
Q

What does the ANA titer represent?

A

The last dilution at which the ANA pattern is detectable.

The higher the number, the higher the levels of the autoantibody that is being picked up

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6
Q

Importance of ANA for SLE?

A

High titers of ANA have high sensitivity (98%), and low specificity (90%) and the NPV is high (99%). The PPV though is only 30-40% for SLE.

  • ~2/3 of + ANAs in a general medical population will be a/w dz other than SLE
  • Rare that a negative ANA will have SLE
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7
Q

What percent of patients w/ SLE are negative for ANA?

A

1-2%

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8
Q

What is the PPV of ANA for the detection of SLE?

A

30-40% and NPV is 99%

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9
Q

What is the most sensitive serologic test for SLE?

A

ANA

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10
Q

What ANA patterns are a/w SLE?

A

Homogenous and peripheral

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11
Q

How often is ANA + in SCLE and what type of ANA pattern is seen?

A

60-80% and speckled/particulate ANA pattern

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12
Q

What percentage of patients w/ DLE have + ANA

A

5-25%

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13
Q

Significance of the ssDNA antibody?

A

This one can suggest a risk for developing SLE in DLE patients.

also seen in linear morphea

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14
Q

Significance of the C1q antibody?

A

Severe SLE and hypocomplementemic urticarial vasculitis

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15
Q

Significance of the dsDNA antibody?

A

Highly specific test for SLE, a/w LE nephritis. Useful for monitoring nephritis activity

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16
Q

What is the significance of the U1RNP antibody?

A

It is always + in mixed connective tissue dz (required for dx)

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17
Q

What is the significance of the Ro/SSA antibody?

A

+ in neonatal LE/congenital heart block (99%); SCLE (75-90%), primary SjS (70); a/w photosensitivity

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18
Q

Which antibody is + in 99% of cases of neonatal LE/congenital heart block

A

Ro/SSA

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19
Q

Significance of the cardiolipin antibody?

A

Antiphospholipid syndrome in SLE.

  • Recurrent abortions, thrombocytopenia, hypercoagulable state, livedo reticularis, leg ulcers, acral infarction, hemorrhagic cutaneous necrosis
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20
Q

Significance of the anti-histone antibody?

A

Drug-induced SLE

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21
Q

Significance of the anti-smith antibody?

A

Highly specific for SLE; higher prevalence in African Americans and Asians (30-40%)

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22
Q

Significance of the anti beta2 glycoprotein antibody?

A

High risk of thrombosis in SLE; primary antiphospholipid syndrome

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23
Q

Significance of the anti rRNP antibody?

A

Highly specific for SLE; a/w neuropsychiatric LE

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24
Q

What is the significance of the anti-Ku antibody?

A

Overlap syndromes with DM/PM and systemic sclerosis. Thought to be potentially associated with myositis in SLE cases

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25
Q

Which antibodies are high specific for SLE?

A

dsDNA, Smith, rRNP

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26
Q

What two proteins make up the Ro antigen?

A

Ro52 and Ro60

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27
Q

Which of the Ro antigens is cytoplasmic and which is nuclear?

A

Ro52 is cytoplasmic and the 60kD (Ro60) is nuclear

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28
Q

Which of the Ro antigens is more pathogenic?

A

Ro52 is more pathogenic and clinically significant

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29
Q

What happens if the patient is negative for 60kD (nuclear) but + for the 52kD (cytoplasmic) antigens?

A

Then the interpreter may report a negative ANA

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30
Q

What do the anti-SSA/ro and Anti-SSB/La antibodies react against and where are they located in the cell?

A

These react against proteins present in human cytoplasmic RNP that are found in both the cytoplasm and nucleus

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31
Q

Why are the Ro and La antibodies often both positive?

A

These are a “linked set” of autoantigens b/c both are present on the same RNP particles

Both are often + due to epitope spreading

32
Q

Even though the Anti-SSA/ro and Anti-SSB/La antibodies are often both present which one is more likely to be present first/alone?

A

the Anti-SSA/Ro is the one that is more commonly + by itself or present first.

33
Q

What antigens and diseases are a/w the homogenous phenotype of the ANA?

A

Antigen: dsDNA, Histones

Disease: SLE, DLE, RA

34
Q

What antigens and diseases are associated with the rim/peripheral phenotype of the ANA?

A

Antigen: native DNA or deoxynucleoprotein

Disease: Most consistent with SLE

35
Q

What antigens and diseases are associated with the speckled pattern of ANA?

A

Antigens: Ro/SSA, La/SSB, RNP, Sm, Scl-70

Disease associations: SS, MCTD, SLE, scleroderma

36
Q

What antigens and diseases are associated with the speckled look of the ANA?

A

Antigens: PM/Scl

Diseases: Scleroderma

37
Q

What antigens and diseases are associated with the Cytoplasmic phenotype of the ANA?

A

Antigens: tRNA synthetases, Jo-1, Mitochondria, Smooth Muscle

Diseases: polymyositis/dermatomyositis, primary biliary cirrhosis, autoimmune hepatitis

38
Q

What drugs are a/w drug-induced-ANA/SLE?

A

Procainamide, Hydralazine, Isoniazid, Chlorpromazine, Phenytoin, Quinidine, Methyldopa, Minocycline

39
Q

What antibodies are + in Drug-induced SCLE?

A

Anti-Ro/SS-A (80%), Anti-La/SS-B)

40
Q

What does the skin eruption in Drug-induced SCLE look like?

A

Skin ALWAYS involved; photosensitive papulosquamous eruption (psoriasiform to lichenoid); rare to have systemic involvement

41
Q

What drugs commonly cause drug-induced SCLE?

A

HCTZ, terbinafine, griseofulvin, NSAIDs, CCBs, Antihistamines, PPI’s, docetaxel, ACE inhibitors, TNF-a inhibitors (etanercept most common)

42
Q

What type of antibodies develops in the use of TNF-a inhibitors?

A

So TNF-a blockade is associated with induction of autoantibody: often ANA and dsDNA

Clinical significance of this is unknown

43
Q

How long does it take on TNF-a inhibitors before autoantibodies form usually?

A

8-20 months

44
Q

Which TNF-a inhibitor is most likely to cause autoantibodies?

A

Infliximab, then adalimumab/entancercept

45
Q

What sx’s occur with the autoantibodies generated by TNF-a blockade?

A

Antibodies = ANA and dsDNA –> lupus-like syndrome: butterfly rash (ACLE), SCLE, and DLE as well as small vessel vasculitis and chilblains

Also: phlebitis (with anti-cardiolipin antibodies), leukopenia, thrombocytopenia, serositis, fever, weight loss, asthenia. Arthritis is a common, renal involvement is rare

46
Q

How does TNF-a inhibitor-induced lupus differ from typical drug-induced lupus?

A

Skin manifestations are more prominent

ANA and dsDNA + are more common than anti-histone +

Development of aAb seems to be clinically insignificant

47
Q

Should you screen for an ANA before starting a TNF-a inhibitor?

A

NOT recommended

48
Q

What is the significance of p155/140 (TIF-1y) antibodies?

A

Clinically amyopathic DM and cancer-associated DM in adults. It is also associated with severe dz in adults and kids.

49
Q

What is the significance of the NXP-2 antibody?

A

Juvenile DM w/ calcinosis

50
Q

What antibodies are associated w/ anti-synthetase syndrome, myositis, mechanics hands, arthritis, Raynaud’s phenomenon, severed ILD?

A

Aminoacyl tRNA syntheases: Anti-Jo1, Anti-PL7, Anti-Pl12, EJ/OJ

51
Q

What are the 4 aminoacyl tRNA synthetase antibodies?

A

Anti-Jo1, Anti-PL7, Anti-PL12, EJ/OJ

52
Q

What is the significance of the anti-Mi-2 antibody?

A

It is against helicase–> classic DM skin findings, mild muscle disease, good response to treatment

53
Q

Significance of the MDA5/CADM-140 antibodies?

A

Against MDA5 (anti-melanoma differentiation-associated gene 5), clinically amyopathic dermatomyositis with rapidly progressive ILD in adults and kids.

also distinctive skin findings: skin/oral ulcers, palmar papules, mechanics hands, panniculitis

54
Q

What are the unique skin findings associated w/ Anti-MDA5/CADM-140 (anti-melanoma differentiation-associated gene 5) antibodies?

A

Skin/oral ulcers, palmar papules, mechanic’s hands, panniculitis

55
Q

Significance of the SRP antibody?

A

Fulminant dermatomyositis/polymyositis w/ cardiac involvement, poor prognosis

56
Q

What is the significance of the centromere antibody?

A

Most specific antibody for CREST or limited cutaneous systemic sclerosis.

a/w pulmonary HTN

57
Q

Significance of the Scl-70?

A

Against DNA topoisomerase I

Most strongly associated with systemic sclerosis with pulmonary fibrosis

58
Q

Significance of the RNA polymerases I/II?

A

High levels correlate with severe skin involvement and renal crisis in primary systemic sclerosis

59
Q

What is the significance of the Anti-RNA polymerase III autoantibody?

A

Increased risk of internal malignancies, associated w/ paraneoplastic systemic sclerosis

60
Q

Significance of the anti-Fibrillarin (U3RNP) antibody?

A

A/w internal organ involvement in systemic sclerosis

61
Q

What is the significance of the ssDNA in morphea?

A

A/w the linear type, correlates w/ disease severity/activity

62
Q

What is the significance of the anti-histones antibodies in morphea?

A

Most prevalent in linear and generalized morphea correlates w/ disease severity/activity

63
Q

What is the molecular target of the rheumatoid factor?

A

Fc portion of the IgG

64
Q

What are the key associations of the rheumatoid factor?

A

Low levels: very nonspecific, may be seen in other connective tissue dz, infections, liver dz, sarcoid, systemic vasculitides

High levels: a/w severe, crippling, erosive RA and extra-articular manifestations of RA like systemic vasculitis, neuropathy.

Mixed cryoglobulinemia types II and III secondary to hep C infection

65
Q

What are the molecular targets of the cyclic citrullinated proteins antibodies (CCP)?

A

CCP proteins in skin like filaggrin and joints

66
Q

What is the significance of the cyclic citrullinated proteins antibodies?

A

A/w severe RA; also a predictor for the development of RA

67
Q

What is the most specific antibody for Sjogren’s syndrome?

A

Alpha-fodrin

68
Q

What is the target of the alpha fodrin antibody?

A

Actin-binding protein (involved in secretion)

69
Q

Significance of the Ro/SSa antibody?

A

Neonatal LE (99% of cases) and SCLE (may be a/w photosensitivity)

70
Q

What antibody defines mixed connective tissue disease?

A

U1RNP

71
Q

What are the hallmarks of DM w/ MDA5 antibodies?

A

Palmar papules, deep cutaneous ulcerations, and oral mucosal pain.

Often amyopathic disease, high risk for ILD

72
Q

What antibody is associated with having Gottron papules, Gottron sign, and shawl sign?

A

Anti-Mi-2

73
Q

Which antibody is a/w patients with dermatomyositis that have concomitant arthritis, Raynaud’s and ILD?

A

Anti-Jo-1

74
Q

Which antibody in dermatomyositis is associated with a higher risk of malignancy and cutaneous sx’s like a heliotrope rash, Gottron’s papules, and flagellate erythema?

A

Anti-p155 (TIF-1y)

75
Q

Which antibody in dermatomyositis is associated with severe symmetric proximal muscle weakness

A

Anti-SRP (signal recognition particle)

DERM (17) Rheumatologic Dermatology (5 decks)

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