MadSci Network: Immunology

Re: Do naive lymphocytes undergo the same procedure as regular lymphocytes?

Date: Mon Dec 16 11:40:49 2002
Posted By: Peter Burrows, Faculty, Microbiology
Area of science: Immunology
ID: 1039662789.Im

When naïve B lymphocytes see antigen, they can undergo clonal 
amplification and differentiate into plasma cells, which are the antibody 
secreting cells. Some of the cells differentiate 
into memory B cells, which have a very long lifespan. The “secondary” 
immune response (the one that occurs the second time you get infected or 
immunized with the same antigen) is more vigorous than the primary immune 
response. There are several reasons for this. 1) 
The frequency of B cells specific for that antigen is increased as a 
result of the clonal expansion and memory cell generation that took place 
during the primary response. 2) The memory cells have often undergone a 
process called somatic hypermutation, which allows them to mutate their 
antigen receptors and the cells with highest affinity (better fit) for 
antigen are selected for survival and clonal expansion. 3) The memory 
cells often have undergone isotype switching so when stimulated by 
antigen they can differentiate into plasma cells making IgG or IgA 
antibodies, rather than IgM antibodies that dominate the primary immune 

Most of the above events in B cells require the help of T cells. Naïve T 
cells also respond to antigen, undergo clonal amplification and 
differentiation into either helper or killer T cells, and they also 
produce memory T cells during the primary response.

“Opsonize” refers to coating of pathogens such as bacteria with 
antibodies, which makes them more readily eaten and destroyed by 
macrophages and other phagocytic cells.

You can find out more about these topics at the website for the Kuby 
Immunology text:

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