Lecture 28: Type II-IV Hypersensativities Flashcards
type II (cytotoxic) hypersensitivity occurs through the production of ____or____ that binds to specific allergens located on______
IgM, IgG, cells
2 phases of cytotoxic hypersensitivity
sensitization phase: exposure to antigen leads to IgM or IgG production
Effector phase: re-exposure to antigen allows allergen specific IgM or IgG to bind, causing immune mediated damage or blocks normal function of the cell
antibody dependent cellular cytotoxicity
NK cells or macrophages killing antibody coated target cells
complement mediated lysis
activation of classical complement pathway to form membrane attack complexes to kill target cells
primary immune mediated hemolytic anemia (IMHA) is considered…
idiopathic/autoimmune
secondary IMHA is caused by….
an immunologic response against non-self antigens that have adsorbed or motified normal RBC membranes
- antibodies bind to antigens on RBCs resulting in lysis
- causes include various infectios agents or drugs (antibiotics)
Transfusion reactions are mediated by antibodies that….
bind and lyse transfused RBCs
manifestations result from intravascular hemolysis of transfused RBCs
what can you do to prevent blood transfusion reactions
perform blood typing and cross-matching tests
neonatal isoerythrolysis
hemolytic disease of newborns
- destruction of newborn RBCs, foals and kittens mostly
neonatal isoerythrolysis is mediated by ______that bind and lyse neonatal RBCs
mismatched blood group maternal antibodies
Direct Coomb’s test detects…
antibodies bound to RBCs
agglutintion test
type III (immune complex) hypersensitivity is caused by what
small immune complexes formed by soluble antigens binding to IgG or IgM
two phases of type III immune complex hypersensitivity
Sensitization and effector phases, occur in continuum
sensitization phase of Type III
initial exposure to antigen, results in immune complex formation that deposit into tissues
effector phase of Type III
immune complex activation of complement & recruitment of inflammatory cells to site of deposition
* inflammation results in increased permeability
immune complexes accumulate in tissues and cause damage due to…
- continual activation of complement
- neutrophil release of tissue damaging enzymes and reactive oxygen intermediates
- platelet aggregation and possible development of thrombi, hemorrhage, edema and necrosis
arthrus recactions =
localized vasculitis
sensitization to antigen results in high levels of______production, leading to _____excess
Antibody, antibody
upon repeated exposure to antigen at same site, _____antibodies form small immune complexes that deposit in the _______ or at the _______
IgG, Vasculature, exposure site
can occur in response to large dose of foreign serum or infections (antigen excess)
systemic vasculitis (serum sickness)
antitoxins, antivenins, bacterial/viral infections
sensitization of horses vaccinated or infected with S.equi may develop a type ____ hypersensitivity reaction (Purpura Hemorrhagia)
Type III
Purpura Hemorrhagica
- horses vaccinated or infected w/ S.equi develop type III hypersensitivity
- immune response occurs against bacterial M protein
- upon exposure to large amount of antigen, small immune complexes form that deposit in the vasculature
- causes tissue damage, fever, depression, anorexia, vasculitis, mucousal hemorrhages
testing for type III hypersensitivity
Immunoassays
type IV (delayed) hypersensitivity is mediated by ____ cells and ______
Th1 and macrophages
hapten-carrier complex
allergen (microbial component, chemical metal, or drug) that complexes with proteins in the skin
Type IV hypersensitivity reactions take ______hours to develop
24-72
in type IV hypersensitivity, initial exposure is often through _________contact w/ the allergen
direct
processing and presentation of hapten carrier complex occurs by
APCs
during the sensitization phase of type IV hypersensitivities, activation and differentiation of helper T cells into TH1 cells causes the development of….?
memory (sensitized) TH1 cells
can also involve activation of CD8 Tcells
what occurs during the effector phase in Type IV hypersen.
APC activation of memory (sensitized) TH1 cells upon subsequent exposure to antigen
release of TH1 cytokines and chemokines to recruit and activate _______and_____ results in ________
macrophages+neutrophils, Inflammation
* INF-y and IL-8
during effector phase of Type IV hypersen., the recuritment/activation of macrophages+neutrophils results in tissue destruction due to the release of….
lytic enzymes and ROIs
prolonged type IV reactions can lead to….
granuloma formulation
- can occur in some persistent bacterial infections
Diagnostic testing for TB
- in vivo testing-intradermal tuberculin rxn
- in vitro testing-INF-y to release
