Question

How does the lag in IgM production compare during a primary and secondary response? Contrast this with the lag seen in IgG production during a primary and secondary response. What does this difference imply about the nature of the secondary response?​

Answer 1

For the first time, if the immune system contacts an antigen its called as primary response and if contacts for second and more times its called secondary response. IgM is one of the largest antibody which will start functioning as antibody in the immune system in response to an antigen and controls B - cell activation.IgG is the common type of antibody in all body fluids and helps to protect against infections.

In primary response a lag phase occurs in which antibodies are not produced as short as 2-3 days but it can be extended to weeks or , months. The first antibody produced is obviously the IgM but IgG is also seen in traces. If another dose of antigen is given there results in an increase in yhe level of response and here IgG is the antibody which are seen in excess and sometimes IgM is seen in traces.

From the given graph its understood that when first antigen Ag X is requiring the immune system to respond the initiation starts with IgM first and traces of IgG is present. But in the secondary response the activity of IgG is very much high compared to the response of IgG in primary condition but the primary response of IgM remains almost the same level or sometimes absent in secondary response.The responses of IgM and IgG are showing low sluggish and short lived in primary case where as the secondary responses are elevated and becomes powerful and prolonged due to IgG.

From these observations the nature of secondary response implies that the importance in the immune system of a body where antibody level of 1000 times or higher can be produced by using the secondary response nature which will produce larger peaks. The secondary phase reflects the actiuity of a large population of memory B cells. These cells responds in rapid manner to the antigens than a normal cell. IgG type is the main antibody responsible for secondary responses. In secondary responses more plasma cells are also produced .