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.

(d) How is active immunity different from passive immunity?

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

Active immunity:
- Occurs when an individual’s own immune system produces antibodies or T-cells to fight off a pathogen or after vaccination.
- This immunity is long-lasting because memory cells are produced.
- Passive immunity:
- Occurs when antibodies are transferred from another individual, such as through breast milk or from an injection of immunoglobulins.
- This immunity is temporary because the body does not produce its own antibodies and has no memory cells.