Hypersensitivity

Hypersensitivity

Hypersensitivity reactions • An immunological responses not controlled by normal regulatory mechanism. • Classification - Gell and Coombs system

Gell and Coombs system • • • •

Type I – immediate (Ig E) Type II – antibody mediated (ADCC) Type III – immune complex mediated Type IV – T cell mediated (delay type hypersensitivity)

OUTLINE • Hypersensitivity -mechanism (Sensitization phase/Effect phase) -clinical manifestation -lab testing

Type I - immediate hypersensitivity IgE-mediated reactions

• Mechanism :

FcεR On mast cells or basophils

Soluble Antigen

Cross linking of Fab

degranulation

Type I - immediate hypersensitivity IgE-mediated reactions • clinical manifestation Atopy: Genetically linkage -Allergies -Allergic rhinitis -Asthma -Atopic dermatitis 「濕疹」 異位性皮膚炎

-Allergic gastoenteropathy

Lack genetic linkage and target organ : -Urticaria 蕁麻疹 -Anaphylaxis 全身性過敏反應 -Anaphylacic shock

Allergic rhinitis

Allergic rhinitis

Type I - immediate hypersensitivity IgE-mediated reactions • allergen Host dust, arthropod, mold, weeds (ragweed), pollen, tree, animal, food, drug, latex Inhalant allergen Contact allergen Food allergen

Type I - immediate hypersensitivity IgE-mediated reactions

• Lab test Skin test In vitro tests Lymphocyte stimulation Intranasal provocative tests 鼻內激發法

Skin test • Cutaneous test (prick test) 扎刺法 pucture small amount to dermis and read after 20 min • Intradermal test 皮下過敏注射 semiquantitative

In vitro tests

體外敏感試驗

• Total IgE : IMMULITE Total IgE (serum IgE only) • Allergen specific IgE RAST : radioallergosorbent test MAST : multiple antigen simultaneous test CAP Immunoblot (AlaBLOT test) --allergen: Ep strip • Eosinophilia : 114-142  300-500/mm3 • ECP (eosinophil cationic protein)

過敏原檢測 Total IgE Test

CAP(混合過敏原群IgE抗體篩檢) Phadiatop, fx5 or CAP(特定過敏原IgE抗體篩檢, 自選)

MAST allergy test

MAST(Multiple Antigen Simultaneous Test) • 同時測定36種抗原 • 使用Chemical Luminescent ImmunoAssay • 半定量 Allergen + tested IgE → Allergen-IgE-(Anti-IgE) → CLA-1 ↑ Anti-IgE*Enzyme • 結果判讀 : 4 : >242 3 : 143~242 2 : 66~142 1 : 27~65 ±: 12~26 - : 0~11

(單位 : LUs) ＊Total IgE>500 IU/mL MAST中的 某些±可能為non-specific binding

Principle • Chemiluminescence Analysis (化學冷光酵素免疫分析法)

Allergen + tested IgE (待測血清) anti-IgE*enzyme Allergy-IgE-(anti-IgE*enzyme) photoreagent CLA-1儀器偵測

MAST allergy test • Introduction ─ 同時測定血清中36種過敏原的特異性IgE抗體 ─ 半定量計量。結果值(LUs淨值)以級數表示 • Result ─ 分四級：0, 0/1, 1, 2, 3, 4 ─ 2級以上表示有意義 • Clinical significance ─ Atopic allergy 屬第一型過敏反應。 ─常見的臨床症狀有花粉熱、氣喘、皮膚炎、蕁麻疹、過敏性休克 ─ 得知患者對不同過敏原的IgE濃度，是診斷和治療過敏的 重要資訊。

• MAST 36種過敏原測試

CAP cellulose carriers β-Galactosidase的抗IgE抗體 反應後,清洗掉未反應物, 加入反應呈色劑 於CAP機器判讀結果。

β-Galactosidase

CAP • 吸入性混合過敏篩檢(23種)及食物性混合過 敏篩檢(6種)

CAP • 吸入性混合過敏篩檢(23種)及食物性混合過 敏篩檢(6種)

UniCAP

UniCAP 原理: FEIA • Fluorescence Enzyme Immunoassay (FEIA)

• Enzyme : β-galactocidase • Substrate : 4-MUG → 4-MU • Stop Solution : 4% Sodium Carbonate

UniCAP • 以FEIA的方法，應用於Autoantibody(Specific IgG)和過敏免 疫系統(Total IgE, Specific IgE)的定量 • Total IgE 檢測體內所含IgE濃度，作為過敏的指標 ─ 測定範圍: 2~5000 kU/L • Specific IgE 檢測不同過敏原產生的特異性IgE抗體 ─ 吸入性混合過敏篩檢(23種)及食物性混合過敏篩檢(6種) Cyclic cirtullinared peptide(CCP) Ab Extractable Nuclear Antigen Ab(ENA)

Eosinophil cationic protein(ECP) 將Anti-ECP固定於cellulose carriers(固相)中, 加入待測血清反應後,清洗掉未反應物,再加入 β-Galactosidase的抗ECP抗體反應後,清洗掉 未反應物,加入反應呈色劑於CAP機器判讀結果。

Anti-ECP 檢驗活化的eosinophil及其產物ECP可追蹤病程,並在 發炎期(ex.急性氣喘)給予抗發炎藥劑,降低發炎,故 檢驗血清中的ECP值是治療成效的指標。

Type I - immediate hypersensitivity IgE-mediated reactions Therapy • Environmental measures : avoid allergen • pharmacological therapies -antihistamine -corticosteroids -cromolyn sodium • Desensitization treatment -Allergen shots (blocking antibody, IgG) • Antibody against free and membrane IgE • Antibody to CD23 (low affinity IgE receptor) • Cytokine intervention

IgG

IgM

Type II – antibody mediated

• Mechanism : Sensitization phase

1.Cell surface antigen Transplanted cell Host cell (autoimmune) Foreign antigen bind to host cells Ag dose not clear from system

2.IgM IgG production (dep. on cytokine)

Effect phase

1.Complement activation chemoattractant C5a C3a Anaphylatoxin C5a Opsonin MAC

2.ADCC by NK 3.Opsonin mediated phagocytosis

Destory cells

IgG IgM

Type II – antibody mediated • clinical manifestation (dep. on cell type) -Hemolytic disease of newborn -Transfusion reactions -Autoimmune disorders -Drug induced reactions -Transplantation

Hemolytic disease of newborn RBC-Rh antigen

Autoimmune disorder • Goodpasture’s syndrome Ab against kidney and lung basement membranes

Antiglomerular basement membrane antibody (Anti-GBM)

renal biopsy even layer on the glomerular basement membrane

• Myasthenia gravis Ab against acetylcholine receptor in neuromuscular junctions down regulation of receptors by endocytosis  muscle weakness

Drug induced reactions ex : penicillin Drug (hapten) Bind to cell surface  Type II hypersensitivity  Cell destruction

IgG

Type III-immune complex mediated

IgM

• Mechanism : Sensitization phase

1.Chronic Ag (soluble) exposure autoimmue disorders or persistent infection 2.IgM IgG production (dep. on cytokine)

Too many immune complexes for phagocytes to remove

Immune complex formation and deposition in the capillary walls

IgG

Type III-immune complex mediated

IgM

Effect phase

1.Complement Anaphylatoxin Opsonin chemoattractant

C5a C3b CR1 C5a C3a

2.Neutrophil phagocytosis damage capillary walls (proteolytic enzyme)

3.Coagulation Vascular permeability PLA aggregation  blood clot formation * 4.Immune complexes penetrate and lodged in capillary walls 5.Vascular occlusion

Type III-immune complex mediated • clinical manifestation -SLE autoantibody, immune complexes deposit in various tissues -Post streptococccal glomerulonephritis S. pyogenes, kidney, “captured antigen” -Serum sickness passive immunization of non human IgG human antibody – non human IgG (ex:horse serum:anti-diphtheria antibodies, antiserum administered following a snakebite ) -Farmer’s lung Ag = spore of Thermophilic actnomycetes -Arthus Reaction

Serum sickness

Arthus Reaction • Ag inject into immunized body • Local inflammatory response due to deposition of immune complexes in tissues. • vaccine boosting(第2劑)

Detection of Immune Complex • C1q binding assay • Raji cell assay • Detection of Cryoglobulins

C1q binding assay

C1q binding assay

False (-)

Small immune complex、 IgE, IgA, IgG4 immune complex

False (+)

Fibrinogen、fibronectin、DNA、 endotoxin、heparin

Raji cell assay • Lymphoblastoid cell line from Burkitt’s lymphoma • C1q C3b C3d and Fcg receptor

• Normal: