Hypersensitivities Flashcards
What are the immune system pathways
Too much
Not enough
Wrong antigen
Training needed
What determines hyper sensitivity reaction
Antigen and entry site
What do B-lymphocytes do
Neutralize microbe
Phagocytize
Activate complement system
What are the types of T Lymphocytes
T-helper
T-cytotoxic
T-regulatory
What do T-helper cells do
Activate macrophages
Cause inflammation
T&B cell activation
What do Cytotoxic T cells do
Kill infected cell
What do T-regulatory cells do
T-lymphocyte responds and causes immune response suppression to prevent autoimmune responses
How many exposures are required to develop a hypersensitivity
1
Could need multiple to develop enough lymphocytes
What are hypersensitivity responses
A response than causes a reaction in the body
How long does it take a hypersensitivity response to occur
Could be immediate or delayed
What are the types of hypersensitivities
Allergic
Cytotoxic
Immune mediated
Delayed (T-cell mediated)
What antibodies are involved with allergic reaction
IgE
What antibodies are involved with cytotoxic reactions
IgG
What antibodies are involved with immune mediated reactions
IgG
Rare
What causes immune mediated hypersensitivities
An antigen coming from oral antibiotics or from an infected source (hep B)
What antibodies are involved with cell mediated reactions
T-cells
What happens first with type 1 reactions
Significant Mast cell degranulation
What are type 1 reactions associated with
Seasonal allergies
What are common symptoms from type 1 reactions
Urticaria
Rhinitis
Conjunctivitis
GI allergy
*anaphylaxis
What would cause someone to have an increased risk of type 1 reactions
An atopic patient has increased production of IgE
What is the most important mediator for mast cells
Histamine
What do H1 receptors do in type 1 reactions
Smooth muscle contraction (bronchospasm) and increased vasodilation/permeability
What do H2 receptors do in Type 1 reactions
Increase gastric acid secretion
Use negative feedback loop
What else do mast cells release in type 1 reactions besides histamine
Leukotriene
Prostaglandins
How does Epi and steroids help during anaphylaxis
Epi- counters the histamine
Steroids-inhibit cytokines, inflammatory response, and enzymes
What is a Type 2 hypersensitivity
Tissue specific reaction
How do type 2 hypersensitivity reactions occur
Outside antigen binds to specific tissue plasma membrane and acts as a target for the reaction
What type of antibody response occurs with type 2 reactions
IgG or IgM
What cellular process can occur to cause type 2 reactions
Cell mediated lysis
Phagocytosis
MAC (osmotic lysis)
NK cells (apoptosis)
Antibodies bind and block receptors
What occurs during type 3 hyper sensitivity reactions
Antibody bonds with circulating antigen and forms antibody-antigen complex
Is type 3 reactions tissue specific?
No- will cause inflammation wherever they deposit
What are examples of type 3 reactions
Reynauds
Systemic lupus
What are classic symptoms of systemic lupus
Malar rash
Oral ulcers
Pericarditis
Pleurisy
Lupus nephritis
Heme disorders
What do antibody-antigen complexes have an affinity for
Glomerular basement membrane
Choroid plexus
Heart
Spleen
Lung
GI tracts
Skin
What are common type 4 reactions
Hashimoto
Type I DM
Poison Ivy
Graft rejection
What happens during a blood transfusion if patient receives uncrossed blood w/antibodies
The antibodies will bind to their own RBC antigens and host erythrocytes will agglutinate
What type of response occurs in blood transfusion reactions
IgM-> the circulating antibodies will already be present against other AB antigens
What is scleroderma
Excessive fibrosis tissue with multiple antibodies and obliterating vascular disease
What can cause scleroderma
Genetic predisposition (epigenetic trigger)
Immune response
Th cells and cytokines increase fibroblast activity
What type of scleroderma is most common
Systemic
What happens to a person with scleroderma
The connective tissue of skin and organs are attacked, causing ischemia and occlusion
What happens when scleroderma lesions become sclerotic
Difficulty opening mouth
Sclerosis of kidneys/GI tract/ lungs
What is X-linked agammaglobinemia
X-linked recessive disease
B-cells are unable to mature appropriately
What happens if B-cells can’t mature correctly
No follicles in spleen/lymph nodes/ plasma
What is a common variable immonodificiency
Most common diagnosed immunodeficiency
Poor antibody response (heterogenous presentation)
What mediated response occurs in common variable immunodeficiency
IgG and other Ig levels along with T-Cell defects
How are common variable immunodeficiency reactions aquired
*can be genetic
From recurrent infections (often respiratory)
Chronic inflammation or from autoimmune disorders
What is IgA deficiency
Normal IgG and IgM but lack of IgA
Weakened mucosal defenses (sinopulmonary and GI infections)
What is IgA deficiency associated with
Other autoimmune diseases
What is hyper IgM syndrome
Low levels of IgG, IgA, IgE
X-linked with defective B-cells
What happens in hyper IgM syndrome
CD4 Th cells cannot bind and therefore cannot activate B-cells
Lack of communication causes no cell mediated response to trigger the humoral response-> decreases macrophage response and causes increased risk of unchecked intercellular infections
What is another name for thymic hypoplasia
DiGeorge syndrome
What is thymic hypoplasia
In appropriate thymus development
What is associated with thymic hypoplasia
Hypocalcemia, tetany, parathyroid hypoplasia
What physical defects are seen with DiGeorge syndrome
Midline facial defects and aortic arch abnormalities
What happens cellularly with DiGeorge syndrome
Decreased T-Cells (B-Cells are normal)
What is the function of IgA antibodies
First line of defense for microbes entering the body
Found in mucous membranes of lung and GI tract
IgD function
On surface of mature B cells for antigen recognition
IgE function
Binds to mast cells and subsequently the antigen causing a release of Mast cell party packs = allergy symptoms
IgG function
Major antibody in the blood
Promotes target cell lysis& phagocytosis
Helps neonatal immunity
IgM function
First antibody class produce to respond to antigen
Lives on mature B cell surface to act as antigen receptor
