Question

1. What’s the difference between a primary immune response and secondary immune response? Answer both in terms of the physiological responses and in terms of the mechanism by which it is achieved.

   Adaptive immunity is a response to a specific antigen.
   How does the adaptive immune system mount a specific response to an invading antigen?

   How is it possible to mount such a response to a wide array of antigens?
   

Answer 1

Difference between Primary and secondary immune response:

Primary immune response	Secondary immune response
Occurs due to primary contact with an antigen	Occurs due to subsequent exposure of the same antigen
Responds to the antigen: native B cell and T cell	Memory B cells
7-10 days is required for the antibody level to reach at peak.	3-5 days is required for the antibody level to reach at peak
Lag phase is 4-8 days	Lag phase is 1-4days
Longer time is necessary to built the immune response	Shorter time is necessary as compared to primary immune system
A few antibodies are produced here	100-1000 antibodies are produced here
Happens mostly in the spleen and lymph nodes	Normally occurs in the bone marrow and then spleen and lymph nodes come
Antibody level is rapidly declined	Antibody level takes longer time to decline
IgM is produced in large amount and IgG in small amount.	IgG is produced in large amount and IgM is in short amount.
Here thymus dependent and thymus independent antibodies are involved	Here thymus dependent antibodies are involved only

Adaptive immunity as a response to a specific antigen:

The adaptive immune response have the ability to specifically recognize and produce a response to a different types of antigens. antigens are present on the surface of B and T lymphocytes and are recognized by the receptors. Adaptive response have the another ability to distinguish between the self-antigen and foreign antigens. When T and B cells become mature, mechanisms in place that prevent them from recognizing self-antigen, preventing a damaging immune response against the body.

It is possible to mount such a response to a wide array of antigens by the follwing way: