Disorders of the Immune System - Practice Questions & MCQ

Allergies:

• The exaggerated response of the immune system to certain antigens present in the environment is called allergy. 
• The substances to which such an immune response is produced are called allergens. 
• The antibodies produced to these are of IgE type. 
• Common examples of allergens are mites in dust, pollens, animal dander, etc.
• Symptoms of allergic reactions include:
  • sneezing, 
  • watery eyes, 
  • running nose, 
  • difficulty in breathing.
• Allergy is due to the release of chemicals like histamine and serotonin from the mast cells.  
• For determining the cause of the allergy, the patient is exposed to or injected with very small doses of possible allergens, and the reactions studied. 
• The use of drugs like antihistamine, adrenaline and steroids quickly reduce the symptoms of allergy.

Auto Immunity:

• Memory-based acquired immunity evolved in higher vertebrates based on the ability to differentiate foreign organisms (e.g., pathogens) from self cells. 
• While we still do not understand the basis of this, two corollaries of this ability have to be understood. 
• One, higher vertebrates can distinguish foreign molecules as well as foreign organisms.
• Most of the experimental immunology deals with this aspect. 
• Two, sometimes, due to genetic and other unknown reasons, the body attacks self-cells.
• This results in damage to the body and is called auto-immune disease. 
• Rheumatoid arthritis which affects many people in our society is an auto-immune disease.