Primary and Secondary Immune Responses: What’s the Difference?
During an initial immune response, antigen activates naive B cells, which then develop into antibody-secreting cells which make antibodies unique for the antigen that triggered the response. While the same antigen stimulates memory B cells, a secondary immunological response is induced, resulting in the generation of more specific antibodies than in the first response.
Differences Between Primary and Secondary Immune Response
| Characteristics | Primary Immune Response | Secondary Immune Response |
| Definition | The primary immune response is the reaction of the immune system when it comes into contact with an antigen for the first time. | The immune system’s reaction when it comes into contact with an antigen for the second and subsequent time is known as secondary immunological response. |
| Appearance | It is most commonly detected in lymph nodes and the spleen. | The bone marrow is the most affected, followed by the spleen and lymph nodes. |
| Occurrence | This occurs as a result of the antigen’s initial contact. | This occurs after a second and subsequent encounter with the same antigen. |
| Antibody Peak | The antibody level reaches its peak in 7-10 days. | The antibody level reaches its peak in 3-5 days. |
| Affinity of Antibody | They have a poor affinity for the antigens they are exposed to. | They have a strong preference for their antigens. |
| Responding Cells | B and T cells are naive | Memory B cells |
| Antibodies | The major immune response involves both thymus-dependent and thymus-independent antibodies. | In the secondary immune response, only thymus-dependent antibodies are involved. |
| Lag Phase | For a long time (4-7 days) | In summary (1-4 days) |
| Types of Antibodies | During the main immunological response, a considerable amount of IgM and a modest amount of IgG are produced. | During the secondary immune response, a considerable amount of IgG and a little amount of IgM, IgA, and IgE are created. |
| Amount of Antibody | In the first immune response, only a few antibodies are generated. | The subsequent immune response produces 100-1000 times extra antibodies. |
| Strength of the Response | A significant amount of IgM and a minor amount of IgG are produced during the major immunological response. | A significant amount of IgG and a minor amount of IgM, IgA, and IgE are produced during the secondary immune response. |
| Antibody level | The antibody level drops to the point where it may be undetectable. | Antibody levels tend to remain elevated for a longer period of time. |
Primary and Secondary Immune Response Citations
- https://www.mytutor.co.uk/answers/867/A-Level/Biology/What-is-the-difference-between-the-primary-and-secondary-immune-response
- http://pediaa.com/difference-between-primary-and-secondary-immune-response/
- https://www.differencebetween.com/difference-between-primary-and-vs-secondary-immune-response/
- http://www.yourarticlelibrary.com/difference/difference-between-primary–immune-response-and-secondary-immune-response-explained/11492
- http://www.yourarticlelibrary.com/immunology/difference-between-primary-and-secondary-immune-response-immune-response/27758
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