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; it is called specific immunity too. Acquired immunity is characterised by memory. Antibodies are specific to antigens and there are different types of antibodies produced in our body: they are IgA, IgE, IgG, IgC, and IgM. It shows primary response when it encounters the pathogen for the first time and secondary response during the subsequent encounters with the same antigen/pathogen.

(c) The organ transplants are often rejected if not taken from suitable compatible persons. [(i)] Mention the characteristic of our immune system that is responsible for the graft rejection. [(ii)] Name the type of immune response and the cell involved in it.

Hint:

In organ transplants, immune rejection occurs when the recipient's immune system recognizes the donor tissue as foreign due to differences in MHC molecules. Cell-mediated immunity, involving T-cells, plays a key role in this process.

Answer 1

(i) Characteristic of the immune system responsible for graft rejection:
- The immune system's ability to recognize "self" from "non-self" antigens is responsible for graft rejection.
- This is due to the presence of Major Histocompatibility Complex (MHC) molecules, which are unique to each individual. If the donor’s MHC is different from the recipient’s, the immune system recognizes the graft as foreign and mounts an immune response against it.
(ii) Type of immune response and the cell involved in it:
- The type of immune response is Cell-mediated immunity.
- The primary cells involved are Cytotoxic T-cells (CD8+ T-cells), which directly attack and destroy the foreign cells (graft).