Question

Immunity in our body is of two types (i) Innate immunity, and (ii) Acquired immunity. Innate immunity is a non-specific defence mechanism, whereas Acquired immunity is pathogen specific. Acquired immunity is characterised by memory. Antibodies are specific to antigens and there are four types of antibodies produced in our body - IgA, IgE, IgG and IgM. It shows primary response where it encounters the pathogen for the first time and secondary response during the subsequent encounters with the same antigen/pathogen. These immune responses are carried out with the help of two special types of lymphocytes present in the blood.

The organ transplants (grafts) are often rejected if not taken from suitable compatible persons. Mention the characteristic of our immune system that is responsible for the rejection.

Hint:

Think of self versus non-self recognition by T-cells.

Answer 1

Step 1: Understanding the question:
A graft from an unmatched person is rejected. We need the property of the immune system behind this.

Step 2: Explanation:
The immune system can tell self from non-self. A foreign graft carries non-self antigens.
This recognition is done by the acquired, cell-mediated immune response, carried out by T-lymphocytes.

Step 3: Why it matters:
Tissue matching, blood group matching and immunosuppressants are used to reduce this response.

Final Answer:
The ability to distinguish self from non-self (cell-mediated immune response by T-cells).