Immunology

• What type of cells are involved in allergic reactions?

  Mast cells, basophils, and eosinophils

  
• What happens during the sensitization phase of an allergic reaction?

  The host is exposed to an allergen for the first time, priming mast cells

  
• What is the role of antigen-presenting cells (APCs) in the sensitization phase?

  APCs uptake the allergen and migrate to lymph nodes to present it to naïve CD4 T cells

  
• What cytokines do activated naïve CD4 T cells produce during the sensitization phase?

  IL-4, IL-5, IL-9, and IL-13
• What is the function of IgE in allergic reactions?

  IgE binds to mast cells, basophils, or eosinophils

  
• What is the half-life of circulating IgE in the blood?

  1. 3 days
• How long is IgE stable when bound to their receptors?

  Stable for weeks
• What occurs during the effector phase of an allergic reaction?

  The host mounts an immune response against the allergen upon repeat exposure

  
• What mediators are released during the early phase of an allergic reaction?

  Preformed mediators including histamine from mast cells

  
• What are the symptoms of the early phase of an allergic reaction?

  Vasodilation, edema, and other symptoms due to histamine release

  
• What characterizes the late phase reaction of an allergic response?

  Infiltration of eosinophils, basophils, neutrophils, and TH2 cells

  
• What are the mediators of tissue injury in allergic reactions?

  Vasoactive amines, lipid mediators, cytokines, and enzymes
• What are some physiological responses and symptoms of allergic reactions?

  Cramping, red and itchy eyes, sneezing, and swelling
• What can fluid loss from circulation during an allergic reaction lead to?

  Circulatory collapse (hypotensive shock) and death
• What is a common treatment for allergic reactions?

  Antihistamine over-the-counter medication
• What is the role of epinephrine in allergic reactions?

  Epinephrine is used to treat severe allergic reactions
• What are the phases of allergic reactions?

  1. Sensitization phase

  • Host exposed to allergen for the first time

  1. Effector phase

  • Early phase: Immediate hypersensitivity reaction
  • Late phase: Inflammatory process with cell infiltration

  
• What are the differences between an over-active and under-active immune system?

  • Over-active: Auto-immunity, inflammatory responses, allergies
  • Under-active: Genetic conditions, drug-induced, UV light effects, immunosenescence, malnutrition, infections, cancer
• What is a genetic condition that can lead to an underactive immune system?

  Severe combined immunodeficiency (SCID)
• What factors can induce an underactive immune system?

  Drug-induced immunosuppression, UV light, malnutrition, and infections
• What is the term for the aging-related decline in immune function?

  Immunosenescence
• How does cancer affect the immune system?

  Cancer can lead to dysfunction of B cells
• What is the term for an immune system that is functioning normally?

  Normally-active immune system
• What are some examples of normally-active immune system responses?

  Bacterial infection, viral infection, vaccination, and transplant rejection
• Allergic reactions occur when the immune system mistakenly identifies harmless substances as threats.
• The immune system is the body's defense against foreign substances.
• Antigens are molecules that trigger an immune response, while antibodies bind to antigens and neutralize them.
• Hypersensitivity reactions can be immediate (type I) or delayed (types II through IV).
• Autoimmunity happens when the immune system attacks healthy tissues instead of pathogens.
• Inflammation is part of the immune response and involves swelling, redness, heat, pain, and loss of function.
• Food allergies are less common than other types of allergies but can be more severe due to their potential impact on vital organs such as the heart or lungs.
• Immune tolerance occurs when the immune system recognizes self-antigens and doesn't attack them.
• A hypersensitivity reaction is an exaggerated response by the immune system to a substance or stimulus.
• Hay fever symptoms include sneezing, runny nose, itchy eyes, and congestion.
• An allergy occurs when the immune system overreacts to something it perceives as dangerous.
• The most common type of allergy is hay fever (allergic rhinitis), which affects about one in five people worldwide.
• The most common type of food allergy is caused by peanuts, followed by tree nuts, fish, shellfish, wheat, soy, milk, eggs, and sesame seeds.
• Allergic rhinitis is caused by exposure to pollen from trees, grasses, weeds, molds, dust mites, animal dander, cockroaches, and insect venom.
• Atopic dermatitis, commonly referred to as eczema, is associated with dry skin and itching.
• Asthma is characterized by airway inflammation and hyperresponsiveness.