New Immuno Slides - Clinical Immunology Does It Matter
Download New Immuno Slides - Clinical Immunology Does It Matter...
Clinical Immunology: does it matter? Conleth Feighery Department of Immunology
Medical disorders Broad classification 1. Caused by infection - bacterial, viral etc 2. Malignant disorders 3. Inflammatory disorders 4. Genetic 5. Vascular 6. Metabolic
Immune response in …. Infection - bacterial, viral etc 2. Malignant disorders 3. Inflammatory disorders 4. Genetic disorders - some 5. Vascular disease? Immune system frequently plays a key role in disease pathogenesis 1.
Infection Elimination dependent on immune response Disease manifestations frequently caused by the response - inflammation All features caused by response eg hepatitis B infection
Malignancy Symptoms due to physical presence of tumour Tumour control now considered to involve the immune response Releasing immunity to tumour antigens - now one of big hopes for therapy Release the Hounds! Activating the T-Cell Response to Cancer; Mario Sznol, M.D., and Dan L. Longo; NEJM, Dec 6, 2015
Inflammation Chronic inflammation responsible for many conditions Cause of inflammation commonly unknown Disease often labeled (loosely) as “auto-immune”
Allergy – acute inflammation Very common ~ 10% of population Specific type of immune response IgE, mast cells, allergen Called - Type 1 hypersensitivity Sometimes fatal
Can you name an autoimmune disease; why? Crohn’s disease Rheumatoid arthritis Sarcoidosis Coeliac disease Type I diabetes mellitus Graves’ disease Multiple sclerosis
Auto-immunity Overused term? Any unexplained inflammatory diseases? “Immune mediated” better term Certain features typical in “classical” auto-immune disease
Classic auto-immune disorders Typical features Female preponderance Auto-antibodies associated MHC genes linked; other genes also Respond to immunosuppressives No known aetiology
Systemic lupus erythematosus Classic ‘prototype’ auto-immune disease Female:male 9:1 Lots of auto-antibodies ! MHC association - HLA-DR3 Responds to immunosuppressives No known aetiology
Systemic lupus erythematosus So-called “connective tissue disease” - CTD Many other CTDs May have features of SLE Examples Sjogren’s syndrome Scleroderma Anti-phospholipid syndrome Rheumatoid arthritis
Some illustrative cases
Case 1 24 year old female chef Multiple purpuric lesions on trunk, pelvis, legs Hobby - sky diving Previously well but DVT diagnosed - 2 years previously
Case 1 What diagnoses come to mind? What further questions? What tests would like initially?
Case 1 FBC Hgb - 10g/dl WCC - 3 x 109/l Platelets - 10 x 109/l Comment! Additional tests?
Case 1 PTT - 14, normal 12 seconds APTT - 47, normal 28 seconds What range of diagnoses? What tests should be performed
Case 1 Idiopathic thrombocytopaenic purpura Anti-phospholipid syndrome - APS APS - thrombosis, thrombocytopaenia, miscarriages Prolonged APTT
Case 1 APS - thrombosis, thrombocytopaenia, miscarriages Prolonged APTT Case 1 has many suggestive features Get more confirmatory evidence?
Case 1 Does this patient have auto-immunity? Is it a connective tissue disease? Would auto-antibody tests help? Anti-nuclear antibodies – present in most CTDs
Antinuclear antibody test
ANA test Helpful, but not specific for SLE, CTD Titre useful – can ignore low titres eg 1/40, 1/80 …… Pattern of staining – limited value except “centromere” pattern – found in CREST
Case 1 – more results Anti-nuclear antibody + If diagnosis is anti-phospholipid syndrome, test for anti-phospholipid antibodies Cardiolipin antibodies ++ (IgG)** Beta-2 glycoprotein antibodies ++ ** Lupus anticoagulant ++ **reproducible when retested!
Case 1 Treatment? Immunosuppression Corticosteroids - prednisolone Azathioprine Intravenous immunoglobulin Anti-coagulation ??
Case 2 29 year old male Dyspepsia, heartburn Certain foods exacerbate - fatty foods Investigated elsewhere - barium meal diagnosis of IBS = irritable bowel syndrome
Case 2 Additional history ? What tests would you like to perform ?
Case 2 FBC - Hgb 10.3g/dl; MCV - 78; ESR, C-reactive protein normal Biochemistry screen normal What diagnoses should be considered ? What further tests would you order ?
Case 2 Iron deficiency anaemia Blood loss - peptic ulcer disease, inflammatory bowel disease Malabsorbtion - coeliac disease, bacterial overgrowth etc. Auto-antibodies?
Endomysial antibody test
> 99% specific for coeliac disease
Case 2 Diagnosis - coeliac disease Antibody tests - tissue transglutaminase, endomysial aby Biopsy of small intestine - findings can be subtle! Mistaken diagnosis of IBS common
Destruction of villi - “atrophy”
Coeliac disease Treatment – gluten free diet Common disorder, 1% of population Female > male 2:1 Specific auto-antibody Is it an auto-immune disorder? Does it matter!
Coeliac disease - genes Very strong association with HLA-DQ2 and DQ8 Possession of DQ2 or DQ8 essential for disease to develop Gluten fractions bind to these molecules, initiate T cell response
Auto-immune diseases - types ORGAN SPECIFIC Endocrine diseases – thyroid, adrenal Intestinal disease – coeliac disease Liver disease – primary biliary cirrhosis CNS disease – multiple sclerosis Blood components – platelets – ITP Kidney – anti-GBM disease
Auto-immune diseases - types NOT ORGAN SPECIFIC Multiple structures targeted – Systemic lupus erythematosus Rheumatoid arthritis Vasculitic diseases - GPA
Auto-immunity - causes Normally ‘immune tolerance’ prevails Thymus – deletion of auto-reactive cells Periphery – regulation of immune response
Auto-immunity - causes Thymus – deletion of auto-reactive cells Periphery – regulation of immune response
BUT Potential of auto-reactivity constant Release of ‘hidden’ self-antigens Infectious agents with similar antigens – cross reactivity
Case 3 -19 year old female Recurrent ear infection, multiple ENT procedures Chronic sinusitis Became systemically unwell, raised temp Joint pain, skin rash Haematuria noted
19 year old female Systemically unwell – hospital admiss. DIAGNOSIS? Immune deficiency? Connective tissue disease? Lupus? Vasculitis? Auto-antibody tests?
19 year old female Vasculitis? Finding of haematuria – suggests systemic inflammatory disorder with renal involvement Potential diagnoses include SLE and condition called GPA = granulomatosis with polyangiitis
Anti-neutrophil cytoplasmic ab.
Vasculitis disorder Sensitive++, specific+++
19 year old female GPA = granulomatosis with polyangiitis Auto-immune disease Highly specific autoantibody test ANCA test – anti-neutrophil cytoplasmic antibody; 95% specific Very strong association with HLA-DP Early diagnosis is critical
GPA presenting features
Auto-antibodies and autoimmune disease Classic finding in auto-immune disease Often very helpful in diagnosis In many diseases, clinical and other test findings often variable, inconclusive Antibodies pathogenic? Other immune components eg T cells may be primarily responsible
Pathogenic auto-antibodies Graves’ disease Myasthenia gravis Skin disease – pemphigus vulgaris
Auto-immune thyroid disease
specific auto-antibody to TSH receptor causes disease
Antibody destroys acetylcholine receceptor
Clustering of auto-immune diseases
Anti-nuclear antibodies Always found in SLE patients “high sensitivity” Also found in many other disorders “low specificity”
Antinuclear antibody test - many patterns
ANA centromere pattern
Specific patterns may indicate likely diagnosis, as here in CREST
Anti-nuclear antibodies React with multiple antigens Can extract specific antigens and test auto-antibodies further Called Extractable nuclear antigens – ENA dsDNA antibodies
Antibody to double stranded DNA
Crithidia luciliae – kinetoplast contains dsDNA
Anti-dsDNA antibodies Found in 30% of SLE patients “low sensitivity” Never found in other disorders “v. high specificity”
Auto-antibodies to ENA Series of extractable antigens Assist diagnosis of several CTDs Classic example is Sjogren’s syndrome “anti-Ro” antibody
Sorting out CTD diseases Many connective tissue diseases have overlapping features Attempting specific diagnosis is important in selecting therapy and assessing prognosis Majority are antinuclear antibody positive Distinguishing between scleroderma and milder variant, CREST is an example
Extractable nuclear antigens Sorting out the ANA + disorders ….. Antibodies to specific nuclear components Helps distinguish different types of CTD Diseases include CREST and scleroderma Sjogren’s disease and SLE When myositis is a feature
CREST and scleroderma Antibodies to ENA antigen, Scl 70, is found in 30% of scleroderma patients Not found in CREST patients Scl 70 = enzyme called Topoisomerase I
ENA are complex autoantigens Different components may be target of autoantibody eg the Ro antigen
Sjogren’s syndrome autoantigens
Patients typically have anti-Ro 60 antibodies
Sjogren’s syndrome – Ro+
Sjogren’s syndrome Inflammation of exocrine glands Decreased saliva, oral secretions Caries++ ANA category antibody called “Ro” helpful in dx
Patient with polymyositis – Ro pos
Antibody found to be anti Ro 52 positive Also found in Ro 52 found in scleroderma, PBC
Other anti-Ro antibody disorders
Sub-acute cutaneous lupus
Other diagnostic antibodies Anti-mitochondrial antibodies in primary biliary cirrhosis Antibody may be detected before the clinical disease emerges
Mitochrondrial antibody Kidney tubule tissue
Auto-antibody in tissue Best diagnostic test – finding antibody deposits in tissue Dermatitis herpetiformis, gluten sensitive skin disease
Antibody deposits in tissue
IgA deposits in skin papillae – dermatitis herpetiformis
Antibody deposits in skin disease Indirect immunofluorescence Pemphigus vulgaris – IgG, C deposits in epidermis, intercellular Linear IgA disease Bullous pemphigoid – IgG and C3 linear deposition at dermal-epidermal junction
Auto-antibodies of note •
Some are (almost) diagnostic Anti-tTG; anti-dsDNA; ANCA; anti-GBM; anti-PDH
Others are helpful, but not specific - ANA (anti-nuclear antibodies); rheumatoid factor
Case 3 Female, age 30 Urticaria for past 2 years Intermittent Worse pre-menstrually Itch associated Thinks it is related to food
Case 3 Swelling of lips - recent Periorbital oedema Had taken antibiotics 2 weeks earlier Anxious ++ Sister with asthma
Case 3 QUESTIONS What do you call this condition ? What is it caused by ? Is it due to food, drugs ? How do you treat it ?
Case 3 Urticaria/angioedema Common Often unexplained - “idiopathic” “Chronic spontaneous urticaria” Disabling - significant “quality of life” impact
Case 3 Drugs which might be implicated ACE inhibitors NSAIDs, salicylates Antibiotics?
Case 3 THERAPY Anti-histamines Combinations of anti-histamines Push doses Corticosteroids? Self-injectable adrenaline?
Food allergy History – facts that make it likely? What foods? What tests?
Food allergy - history Usually short time lapse after eating food eg. 1 min to 1 hour Symptoms – skin rash/swelling, oral itch, wheeze, nasal stuffiness, diarrhoea, vomiting Atopic
Food allergy - foods Classic – nuts, shellfish Fruits – apple, organge, kiwi …. Wheat ? Dairy products, eggs in children
Food allergy - tests Skin prick with food – 10 min reaction observed* Specific IgE to food* Food challenge * demonstrate sensitisation, not clinical reaction
Angioedema - hereditary
Angioedema – hands
Hereditary angioedema C1-inhibitor defect – C1-inh Genetic defect Low, absence in majority of cases Low levels of C4 at all times Potentially life-threatening