Changes

====Secondary T Cell Dependent Response====

====Secondary T Cell Dependent Response====

*The production of antibody to any antigen ceases within a few weeks of immunisation as the antigen disappears from the body

The production of antibody to any antigen ceases within a few weeks of immunisation as the antigen disappears from the body; However, the animal retains '''immunological memory''' of the antigen which occurs after the primary response - it is seen on the second and subsequent exposures to the same antigen. In effect, there is an expanded pool of memory B and T cells from the first exposure to the particular antigen which permits a shorter lag phase and a longer plateau phase as antibody persists for an extended time. There is a higher antibody titre overall due to cloanal expansion and '''Long-lived memory cells''' which are qualitatively distinct are produced.  Antigen is retained within the immune system on the surface of follicular dendritic cells and this can stimulate the immune system for years.

* However, the animal retains '''immunological memory''' of the antigen

 

*Occurs after the primary response, i.e. the second and subsequent exposures to the specific antigen

The level of [[Immunoglobulin M|IgM]] antibody production in the secondary response is similar to the primary response; the increase in antibody production occurs with [[Immunoglobulin G|IgG]].

*There is an expanded pool of memory B and T cells from the first exposure to the particular antigen  

*Shorter lag phase

*Longer plateau phase as antibody persists

*There is a higher antibody titre overall due to cloanal expansion

*'''Long-lived memory cells''' which are qualitatively distinct are produced  

* Retention of antigen within the immune system  

** On the surface of follicular dendritic cells

** Can stimulate the immune system for years

* The level of [[Immunoglobulin M|IgM]] antibody production is similar to the primary response

* The increase in antibody production occurs with [[Immunoglobulin G|IgG]]

===Plasma Cell Pathology===

===Plasma Cell Pathology===