Question

Read the following passage and answer the questions that follow :

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.

(ii) 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:

The body attacks tissue it sees as foreign; T-cells do this job.

Answer 1

Step 1: Understand the question:
A graft from an unsuitable donor is rejected. The question asks which property of the immune system causes this.

Step 2: Find the property responsible:
Our body can tell self from non-self. Tissue of another person carries foreign markers, so the body treats it as non-self.
This job is done by the cell-mediated immune response, in which T-lymphocytes attack the foreign tissue.

Final Answer:
The ability to distinguish self from non-self, through the cell-mediated immune response of T-lymphocytes, causes graft rejection.