Allergies and Autoimmunity
Allergy is an exaggerated immune response to normally harmless substances, often involving IgE and histamine, while autoimmunity is an immune attack against the body's own tissues.
In one line: Allergy is overreaction to outside; autoimmunity is misdirected attack inside.
Concept Practice Coming SoonUnderstand it
- Allergies occur when the immune system overreacts to allergens such as pollen, dust, or certain foods.
- IgE antibodies and mast cells are commonly involved, and histamine release can cause sneezing, watery eyes, itching, or swelling.
- Antihistamines reduce histamine effects but do not remove the basic tendency to respond.
- Autoimmunity is different: the immune system fails to properly recognise self and non-self, so immune responses damage body tissues.
- Examples include rheumatoid arthritis and lupus.
- Exams often ask students to distinguish allergy from autoimmune disease using target, trigger, and immune mechanism.
Example
Rule to remember
Comparison rule: allergy targets harmless external allergens; autoimmunity targets self tissues due to failure of self-recognition.
See it worked out
Follow the example line by line, then use the same method on new questions.
Worked example
Question: A student has sneezing after pollen exposure.
- 1Is this autoimmunity?
- 2Answer: No. It is allergy because the trigger is an external allergen and symptoms involve hypersensitivity, often linked with histamine.
Method you can reuse
- 1Identify whether the trigger is external or self tissue.
- 2For allergy, mention allergen, IgE, mast cells, histamine, and symptoms.
- 3For autoimmunity, mention loss of self-tolerance and tissue damage.
- 4Give one correct example.
Visual tip
A comparison chart is useful. Labels should include allergen, IgE, mast cell, histamine, self-antigen, autoantibody or autoreactive lymphocyte, and tissue damage.
Check yourself
Answer the question in your head before opening the answer.
Try it yourself
What is the basic difference between allergy and autoimmunity?
Think first, then show answerHide answer
Common wrong answer
Writing antihistamines cure autoimmune disorders is wrong; antihistamines reduce histamine-mediated allergic symptoms.
Don't mix this up
Exam tip
Write it in the exam
Each point is worth about one mark. Write point 1 for a 1-mark question and keep adding points as the marks go up.
How CBSE asks it
Answer plan
- 1
Enough for 1 mark
Allergy is an exaggerated immune response to normally harmless substances, often involving IgE and histamine, while autoimmunity is an immune attack against the body's own tissues.
- 2
Add for 2 marks
Example: Pollen allergy may cause sneezing and watery eyes due to histamine release. Rheumatoid arthritis is autoimmune because immune activity affects joints rather than an external allergen alone.
- 3
Add for 3 marks
Allergies occur when the immune system overreacts to allergens such as pollen, dust, or certain foods.
Concept practice is coming soon
Login to access concept-level MCQs and weak-concept practice as they become available.
Help improve this page
Found something confusing, incorrect, or missing?