Differences between Primary and Secondary Immune Response
S.N. |
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 |
Occurrence |
This occurs in response to the primary
contact of the antigen. |
This occurs in response to the second and
subsequent exposure to the same antigen. |
4 |
Antibody Peak |
The antibody level reaches its peak in 7-10
days. |
The antibody level reaches its peak in 3-5
days. |
5 |
Affinity of Antibody |
Low affinity to their antigens. |
High affinity to their antigens. |
6 |
Responding Cells |
Naive B cells and T cells |
Memory B cells |
7 |
Antibodies |
Both thymus-dependent and thymus-independent
antibodies are involved in the primary immune response. |
Only thymus-dependent antibodies are
involved in the secondary immune response. |
8 |
Lag Phase |
Long (4-7 days) |
Short (1-4 days) |
9 |
Types of Antibodies |
A large amount of IgM and a small amount of
IgG are produced during the primary immune response. |
A large amount of IgG, a small amount of
IgM, IgA, and IgE are produced during the secondary immune response. |
10 |
Amount of Antibody |
Few antibodies are produced in the primary
immune response. |
100-1000 times more antibodies are produced
in the secondary immune response. |
11 |
Strength of the Response |
The primary immune response is usually
weaker than secondary immune response. |
The secondary immune response is stronger. |
12 |
Antibody level |
Antibody level declines to the point where
it may be undetectable. |
The antibody level tends to remain high for
longer. |
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