Type 4 Hpersensitivity Rxns Flashcards
Type w Hypersensitivity reactions are mediated by _______ and utilize _________ antigens
T Cells
Soluble and Insolube
Type of Hypersensitivity in Type 4?
Most are delayed type hypersensitivity
Th1 Type IV reaction.
Name the antigen type, effector mechanism
Soluble antigen
Macrophage Activation
Th2 Type IV reaction.
Name the antigen type, effector mechanism
Soluble Antigen
Eosinophil Activation
CTL Type IV reaction.
Name the antigen type, effector mechanism
Cell Associated Antigen
Cytotoxicity
Example of TH1 cell type four hypersensitivity reactions
Contact Dermatitis
Tuberculin Rxn
Example of TH2 cell type four hypersensitivity reactions
Chronic Ashtma
Chronic Allergic Rhinitis
Example of CTL cell type four hypersensitivity reactions
Contact Dermatitis
Example of a Type 4 allergy response
Poison Ivy
Example of a Type 4 Transplantation Rxn
Acute Rejection
Example of Type 4 mediated autoimmunity
Type I Diabetes
Difference between delayed type hypersensitivity and contct hypersensitivity exposure.
DTH – Proteins Injected into Skin
Contact – Small, Absorbed into Skin
Examples of antigens in Type 4 DTH?
Insect Venom
TB Test
Consequences of delayed type hypersensitivity rxn?
Local Skin Swelling (erythema, induration, cellular infiltrate, dermatitis)
Examples of antigens of Contact hypersentivity
Pentadecacatechol
DNFB
Small Metal Ions (Nickel, Chromate)
Consequences of a Type 4 contact hypersensitivity reaction
Local epidermal reaction
Erythema, Cellular Infiltrate, Vesicles, Intraepidermal Abscess
What happens in gluten-sensitive enteropathy
Gliadin in the GI tract triggers villous atrophy in small bowel, malabsorption
Four types of Type 4 reactions
Contact hypersensitivity
Tuberculin
NK and T-cytotoxicity
Granulomatous
Cytokines involved in Type 4?
IFN-g, TNF-a, IL-3, IL-12, GM-CSF
Diseases associated with granulomatous hypersensitivity? (6)
Leprosy Tuberculosis Schistosomisis Sarcoidosis Crohn's Hypersensitivity pneumonitis
Ways a DTH reaction can be assessed?
Patch Test
Skin Test to Evaluate CMI
What is pentadecacatechol?
The causative agent of contact sensitivity in poison ivy
How does Type 4 rxn sensitivity first encounter play out?
Penetration into skin Modification of self protein Capture by antigen presenting cells presentation in LN Activate native T cells Generation of poison ivy specific T cells
Final result of first poison ivy exposure?
Asymptomatic
How does Type 4 rxn sensitivity play out in 2nd chance
Penetration into skin
modification of self proteins
Captured by APCs, presented in LN
Memory T Activation
Final result of second poison ivy exposure?
Activation of downstream effector cells
Phagocyte recruitment and Inflammation
Where are Langerhan’s Cells located?
Epidermis
Lymphocytes found in skin must express…
Curaneous Lymphocyte Antigen (CLA)
P-/E- Selectin Ligands
Chemokine Receptors (CR4, CCR8, CCR10)
Describe the steps of a skin DTH rxn
Contact sensitizing agent penetrated skin
Taken up by Langerhan’s
Lang. present self peptides haptenated with the contact sensitizing agent to TH1 (releasing more IFNg)
Activated kera. secrete IL1, TNFa, IL-8, IL-9, and MIG
TH1 activation of macrophages to secrete mediators of inflamm
Four downstream effectors secreted by Th1 cells
Chemokines
IFNg
TNFa and LT
IL3/GM-CSF
What to TH1 chemokines do?
Recruit Macrophages
What to TH1 IFNg do?
Activate macrophages, increasing release of inflamm mediators
What do TNFa and LT do?
Increase expression of adhesion molecules on B vessels
Local Tissue Destruction
What does IL-3/CM-CSF do?
Monocyte production by bone marrow cells
How is contact hypersensitivity treated?
Corticosteroids
What do corticosteroids do?
Suppres Inflammatory genes
Induce synthesis of anti-inflammatory proteins
