I understand that when naive B cells are exposed to antigens, they become memory B cells, but what is the functional difference between the two? I've looked at the quite a few article on B cells, but none of them stated the difference clearly enough for me to understand.
2 Answers
The main difference is that memory B cells start an immune reaction much more effective and faster than naive B cells. The reaction is also specific towards the antigen.
The memory B cell has a specific membrane receptor for an antigen. It produces specific antibodies only when exposed to the antigen.
References:
Tangye SG, Avery DT, Deenick EK, Hodgkin PD. Intrinsic differences in the proliferation of naive and memory human B cells as a mechanism for enhanced secondary immune responses. J. Immunol. 2003 Jan 15;170(2):686-94. PubMed PMID: 12517929.
Wikipedia contributors, "B cell," Wikipedia, The Free Encyclopedia, http://en.wikipedia.org/w/index.php?title=B_cell&oldid=612990219 (accessed June 26, 2014).
Naive B cells have not yet been trained by the immune system to recognize specific antigens -therefore the term "naive". Prior to antigen exposure, they must be trained in the bone marrow to recognize certain antigens.
Memory B cells, on the other hand, are formed after antigen exposure and clonal selection. As stated above, they have specific receptors for antigens and can produce antibodies.
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1$\begingroup$ They are actually not trained in the bone marrow, but in germinal centers in the lymphatic tissues. $\endgroup$– Chris ♦Commented Jun 4, 2014 at 19:52