hypersensitivity types 2, 3, 4 Flashcards
Type 2 HSR immune reactant
IgG
Type 2 HSR antigen
cell or matrix associated antigen
cell surface receptor
Type 2 HSR effector mechanism
complement, FCR cells (phagocytes, NK cells)
antibody alters signaling
Type 2 HSR examples
Erythroblastosis fetalis (HDNB)
drug allergies
Graves Disease
Type 3 HSR immune reactant
IgG
Type 3 HSR antigen
Soluble antigen
Type 3 HSR effector mechanism
complement, phagocytes
Type 3 HSR examples
serum sickness
Type 4 HSR immune reactant
Th1 cells
Th2 cells
CTL
Type 4 HSR antigen
Soluble antigen
Soluble antigen
cell-associated antigen
Type 4 HSR effector mechanism
macrophage activation
eosinophil activation
cytotoxicity
Type 4 HSR examples
contact dermatitis, TB
chronic asthma, chronic allergic rhinitis
contact dermatitis
Erythroblastosis fetalis (HDNB)
Rh negative mother, Rh positive fetus
first child minimally affected
Erythroblastosis fetalis (HDNB) treatment
Rhogam (IgG anti-Rh)
Ab2
against hapten modified self antigen: Ag-Ab on cells or on tissue
Type II hypersensitivity
Ab1
against the hapten –may lead to soluble Ag-Ab complex
Type III hypersensitivity
Type 3 HSR due to
deposition of soluble antigen/antibody complexes
Type 3 HSR Immune complex (IC)
Small immune complex
circulate in blood when IC formation exceeds disposal from circulation
Reaction could systemic or localized
ex. SLE
Type 3 HSR diagnosis
Results in depletion of complement in serum:
Level of serum C4 level – diagnosis
Type 3 HSR : Serum Sickness reactions
Direct Immunofluorescent staining
detecting IgG deposition
“Lumpy-bumpy” pattern
Type 3 HSR – Localized : Arthus Reaction
Localized deposition of IC within the skin
Type III HSR :Lung: Hypersensitivity Pneumonitis (HP)
Mediated by IgG
Examples:
farmer’s lung, pigeon breeder’s pneumonitis, cheese washer’s lung, mushroom worker’s lung, laundry worker’s lung, etc
Type 4 HSR Cell mediated
no antibodies involved
Type 4 HSR Sensitization stage
Tho CD4 to Th1 effector cells (most common)
Naïve CD8 to cytotoxic CD8 cells (less common)
Type 4 HSR CD4 vs CD8
CD4:
small mol. (ex.nickel)
Presented to naïve CD4 T cells
CD8:
(ex. poison Ivy)
Tuberculin Reaction
PPD (purified protein derivative) tests exposure to Mycobacterium tuberculosis
Accumulated Th1 and macrophages
Persistent Ag
If antigen persists tuberculin swelling becomes granuloma
Celiac Disease
Gluten from wheat
Type IV hypersensitivity
Clinical Features: malabsorption and diarrhea
