The plasmablasts are sought because they have a high capacity to secrete antibodies, on the other hand they represent the entire repertoire of a patient at time T. The limit of their use is that they do not surface Ig to allow isolate, and that 50% of secreted Ig are IgM.

The memory B cells do not have this limitation, but they represent only a part of the repertoire and their number in the circulation is relatively small.

If researchers seek to isolate these different populations of B cells, it is primarily to clone antibodies that want to study, to do this they must go through an activation spécifique.Les two most commonly used activations are: CD40 activation for plasmablasts and TLR7-9 for memory cells.

But it is very rare to sort cells by FACS specifically because the amount of antibodies retained on the surface of the B cells is too low to be selected on the basis of recognition of the target antigen.

Their secretory capacity is preferred to select, for example by ELISA

You can refer to the following link:-

1. https://www.bdbiosciences.com/documents/Bcell_Brochure.pdf

You can also study the following articles:-

1. Xiao-Song He, Sanae Sasaki, Carlos F. Narvaez, Caiqiu Zhang, Hui Liu, Jennifer C. Woo, George W. Kemble, Cornelia L. Dekker, Mark M. Davis and Harry B. Greenberg. (2011). Plasmablast-derived polyclonal antibody response after influenza vaccination. J Immunol Methods. 2011 Feb 28; 365(1-2): 67–75. doi: 10.1016/j.jim.2010.12.008. 

2. Zhonghua Lin, Nancy Y Chiang, Ning Chai, Dhaya Seshasayee, Wyne P Lee, Mercedesz Balazs, Gerald Nakamura & Lee R Swem (2014). In vivo antigen-driven plasmablast enrichment in combination with antigen-specific cell sorting to facilitate the isolation of rare monoclonal antibodies from human B cells. Nature Protocols 9, 1563–1577. doi:10.1038/nprot.2014.104. 

flow-based sort plasma blasts are committed cells capable of secreting antibodies, unlike the memory B cells which require additional signals and further activations before getting transformed in to plasma cell which are the secretory cells. Secondly the level of purity also gave plasma blast cells an age over the memory B cells.

Thanks all!

There are some papers where antibody-secreting cells have been obtained by sorting memory B cells. It depends on what your goal is (just analysis, or cloning as well?) and your downstream culture system if you plan to obtain secreted IgG. 

For example these guys sorted on CD19+ IgD- IgA- IgM- and obtained IgG-secreting cells using a culture system containing feeder cells with CD40L plus IL-2 and IL-21. http://www.nature.com/nprot/journal/v8/n10/abs/nprot.2013.117.html I have tried a similar setup and it works.