Question

In higher vertebrates, the immune system can distinguish self-cells and non-self. If this property is lost due to genetic abnormality and it attacks self-cells, then it leads to

• A. Graft rejection
• B. Auto-immune disease
• C. Active immunity
• D. Allergic response

Hint:

 Our body can defend itself from most foreign agents as a result of immunity. Immunity can be classified as Innate immunity and Acquired immunity. 

Answer 1

The Correct Option is B

The given question is about the immune system's ability to differentiate between self-cells and non-self (foreign) cells in higher vertebrates. The immune system's primary function is to protect the body against infections and foreign substances. When this system loses the ability to recognize self-cells due to genetic abnormalities and starts attacking them, it leads to an autoimmune disease.

Here's the step-by-step explanation:

1. Immune System Functionality: The immune system distinguishes between self and non-self through specific markers (antigens) present on cell surfaces. Self-tolerance is a critical feature where the immune system does not attack the body's own cells.
2. Genetic Abnormality: Sometimes, genetic mutations or abnormalities result in the immune system failing to recognize the body's own cells as 'self', resulting in an immune response against these cells.
3. Autoimmune Disease: This condition where the immune system attacks its own cells and tissues is known as an autoimmune disease. Examples include rheumatoid arthritis, lupus, and type 1 diabetes.

Now, let's analyze the options:

• Graft rejection: This occurs when the immune system attacks transplanted tissues or organs from a donor, recognizing them as foreign. This is not related to self and non-self recognition in its own body.
• Auto-immune disease: Correct option. As discussed, this involves the immune system attacking self-cells due to loss of self-recognition.
• Active immunity: This refers to the protection gained post-vaccination or recovery from an infection, where the body remembers how to fight the specific pathogen. It is unrelated to self-cell recognition failure.
• Allergic response: This is an overreaction of the immune system to harmless substances (allergens), like pollen or dust. It does not involve attacking self-cells.

Conclusion: The correct answer, given the context of the immune system attacking self-cells due to genetic abnormalities, is "Auto-immune disease."