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39 Cards in this Set

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In type III HS rxns, can complementation be involved?
yes! but they don't have to be
where in the body are immune complexes formed?
liver and spleen
Describe Persistent infection
- infectious diseases such as malaria, leprosy, viral hepatitis, and others may have long-term persistence of the pathogenic organism leading to chronic production of immune complexes
describe autoimmunity
- autoimmune diseases where you have chronic production of auto-reactive antibody can lead to prolonged immune complex formation. The normal clearance systems become overloaded and the immune complexes are deposited in the tissues.
describe a Inhaled antigen and how immune complexes are involved
Immune complexes can form on respiratory surfaces (e.g. alveoli) following repeated exposures to some extrinsic antigens, such as molds, or antigenic material from plants or animals
what is an immune complex?
The product of an antigen-antibody reaction which may also contain complement system proteins
where do immune complexes deposit?
blood vessel walls
how are immune complexes transported to their site of destruction?
Erythrocytes have the receptors for C3b complement protein, and therefore readily bind immune complexes that have fixed complement and transport these complexes to the liver and spleen.
What is an Arthus reaction
A focal hypersensitivity reaction (usually seen in the skin, or in the lungs) upon repeated exposure to some antigenic material, which induces local immune complex formation, complement activation, leading to acute inflammatory responses (increased blood flow, increased capillary permeability, cell infiltration, histamine and other mediator effects, platelet aggregation), and focal necrotizing vasculitis due to local deposition of immune complexes
renal disease could be due to what type of HS rxn?
Type III due to deposition of immune complexes in glomeruli
Arthus reaction
a focal hypersensitivity reaction (skin or lungs) due to repeated exposure to antigen that induces local immune complex formation
what is serum sickness
a SYSTEMIC vasculitis due to systemic deposition of immune complexes
what type of rxn will you see At inoculation site in persons receiving s.c. injections for allergy desensitization
Arthus-type reaction (Type III Hypersensitivity)
what type of rxn will you see At the site of insect bites
Arthus-type reaction (Type III Hypersensitivity)
what type of rxn will you see At the site of drug injections
Arthus-type reaction (Type III Hypersensitivity)
what type of rxn will you see In the early stages of Farmer's lung (= Hypersensitivity pneumonitis)
Arthus-type reaction (Type III Hypersensitivity)
a bump/wheal is associated with what type of HS rxn? general redness?
wheal: Type I (15 minutes)

redness: Type III arthus (takes several hours)
what are the symptoms of serum sickness?
systemic vasculitis of variable severity, characterized by

fever, lymphadenopathy, arthralgias, and dermatitis.
where is Immune complex deposition is most likely to occur?
where there is high blood pressure and turbulence. (e.g., renal glomerular capillaries, choroid plexus, and at sites of bifurcation in artery walls)
what 2 ways can you measure/detect immune complexes?
radioimmunoassay (RIA)

enzyme-linked immunosorbent assay (ELISA) using complement C1q as the bound antigen.
what is the timeframe for type IV hypersensitivity?
"delayed" in the sense that they usually take more than 12 hours to develop
what are teh central mediators of Type IV HS rxns?
T cells
What is contact hypersensitivity? what type of HS rxn is it?
reaction to poison ivy (or nickel) and other haptens, e.g. Allergic Contact Dermatitis, Langerhan’s Cells are important antigen-presenters

Type IV
what is Tuberculin type rxn? type of HS rxn?
seen in the tuberculosis skin test, principally involves monocytes

Type IV
What is a Granulomatous type rxn? type of HS rxn?
probably the most important Type IV response clinically; results from the persistence of microbes or other antigens within macrophages

type IV
What is the role of Langerhan's cells?
they play a role in the sensitization phase of type IV contact reactions

bring the cell to lymph nodes for presentation to T cells
what are haptens again?
too small own their own to produce a response, need something else (like poison ivy)

bind to some self protein (such as Langerhan cell)
what happens in the effector phase of contact type IV rxns? what is primarily responsible?
sensitized T cells respond to antigen and produce inflammatory cytokines (INF gamma for example)

help activate macrophages, etc. all acting on the skin to cause separation of the skin (blisters, vasodilation, irritation of nerve endings)
what is a granuloma?
attempt to close/wall off an infection by the immune system

try to control the spread of infection
what forms multinucleated giant cells?
the fusion of macrophages or epitheliod cells
what are epithelioid cells?
large flattened macrophages that have increased endoplasmic reticulum and form a continuous sheet like an epithelium, and may serve to trap material within the granuloma
if granulomas can wall of infection, why are they problematic?
they can be in a place that obstructs function, such as the lung
3 Diseases typically manifesting Type IV granulomatous hypersensitivity
Tuberculosis (caused by Mycobacterium tuberculosis bacteria)
- Leprosy (caused by Mycobacterium lepra bacteria)
- Leishmaniasis (a one-celled parasite)
Diseases resulting from immune complex formation are divided into three (3) broad groups, what are they?
Persistent infection

Autoimmunity

Inhaled antigen
Where are immune complexes removed from the body? what do this?
Liver and spleen

macrophages are responsible for the removal
What is responsible for transporting immune complexes to the spleen/liver? how do they do this?
RBCs

they have receptors for C3b complement protein, and therefore readily bind immune complexes that have fixed complement
eczema is what type of HS rxn?
IV
Langerhans cells play a role in what type of HS rxn?

what do they do?
Type IV

These antigen-presenting cells activate T cells in a local lymph node and memory cells are produced
if you see Epithelioid cells or Multinucleate Giant cells what are you thinking?
Epithelioid cells :- large flattened macrophages that have increased endoplasmic reticulum and form a continuous sheet like an epithelium, and may serve to trap material within the granuloma

THINK Granulomatous hypersensitivity

TYPE IV