Week 1 - the immune system Flashcards
Type 1 Hypersensitivity
- Mediated by IgE and Mast Cells
- immediate reaction
- Mast cells with antibodies attached bind to the antigen signaling the mast cell to degranulate releasing mediators (histamines) and release eosinophils
What is the function of histamine?
Causes:
- bronchoconstriction
- vasodilation
- increased blood flow
- increased vascular permeability
- swelling and edema
Examples of Type 1 Hypersensitivity Reactions
- Allergies
- Anaphylaxis
- Atopy (predisposition to hypersensitive immune response)
Type 2 Hypersensitivity
IgM or IgG mediated reaction
Macrophages are the primary effector cells.
Antibody binds to target cell and cause inflammatory response resulting in cell destruction or change of function. Antigen/antibody bind on the cell’s surface making it organ specific.
Examples of Type 2 Hypersensitivity Reactions
Grave’s disease - immune diseases causing hyperthoroidism
Blood transfusion mismatch
Rheumatic fever - antibody looks like a “self”, heart cell and attack actual heart tissue
Myasthenia Gravis - receptors of muscles are destroyed or binded to inappropriately resulting in messages not being sent or received resulting in muscle weakness.
Good pasture disease -
Hemolytic anemia -
Type 3 Hypersensitivity Reactions
Antibody mediated reaction.
Immune complex (antigen + antibody) is a medium size forms in the blood or body fluids. These then lodge in the joints, kidneys, causing an inflammatory reaction at the site. When stuck complement is activated, which activates neutrophils (primary effector) causing localized destruction of surrounding tissues.
Examples of Type 3 Hypersensitivity Reactions
Serum sickness - hypersensitivity reaction to drugs.
Arthus reaction - acute, localized, inflammatory response that occurs after vaccination
Systemic Lupus
Rheumatoid arthritis
Type 4 Hypersensitivity Reaction
Cell mediated reaction (T and B cells), a delayed reaction that takes days to manifest causing a skin reaction.
Examples of Type 4 Hypersensitivity Reactions
Contact dermatitis - poison ivy
PPD - tuberculin skin test
DM 1 - destruction of beta cells in the islet of langerhans
Graft/Host disease (transplant rejection)
Sensitization
A process by which a first exposure happens which causes the creation of IgE antigens against the allergen.
A second exposure occurs and the IgE recognizes the allergen and immediately degranulates to release histamines, leukotrienes, and prostaglandins.
Causes smooth muscle contraction in the airways, mucous production and vasodilation.
Primary Immunodeficiency
Caused by a single gene defect in the immune system development. This could include B&T cells, phagocytes, complement. Immune system does not function properly.
Not usually inherited.
Usually appears within first 2 years of life.
Secondary Immunodeficiency
Immune system compromise due to external factors like cancer, medications, chemotherapy, immunosuppressants. (HIV, cancer)
Carcinogenesis
Process of tumor development which begins with a single mutant cell.
Anaplasia
Lack of cell differentiation and function.
Autoimmunity
The immune system mistakes its own healthy tissues as foreign and attacks them. Most autoimmune diseases cause inflammation that can affect many parts of the body. Damage is usually caused by antibodies, T and B cells. Can be familial.
