Question

Differentiate between

Primary and secondary immune responses

Answer 1

Characteristics	Primary Immune Response	Secondary Immune Response
1. Definition	Primary Immune Response is the reaction of the immune system when it contacts an antigen for the first time.	Secondary Immune Response is the reaction of the immune system when it contacts an antigen for the second and subsequent times.
2. Appearance	Appears mainly in the lymph nodes and spleen.	Appears mainly in the bone marrow and then, in the spleen and lymph nodes.
3. Antibody Peak	The antibody level reaches its peak in 7 - 10 days.	The antibody level reaches its peak in 3 - 5 days.
4. Responding Cells	Naive B cells and T cells	Memory B cells
5. Strength of the Response	The primary immune response is usually weaker than secondary immune response.	The secondary immune response is stronger.