Editing B cell (section)

=== Memory B cell activation ===
Memory B cell activation begins with the detection and binding of their target antigen, which is shared by their parent B cell.<ref name=":13">{{cite journal | vauthors = McHeyzer-Williams M, Okitsu S, Wang N, McHeyzer-Williams L | title = Molecular programming of B cell memory | journal = Nature Reviews. Immunology | volume = 12 | issue = 1 | pages = 24–34 | date = December 2011 | pmid = 22158414 | pmc = 3947622 | doi = 10.1038/nri3128 }}</ref> Some memory B cells can be activated without T cell help, such as certain virus-specific memory B cells, but others need T cell help.<ref name=":12" /> Upon antigen binding, the memory B cell takes up the antigen through receptor-mediated endocytosis, degrades it, and presents it to T cells as peptide pieces in complex with MHC-II molecules on the cell membrane.<ref name=":13" /> Memory T helper (T<sub>H</sub>) cells, typically memory follicular T helper (T<sub>FH</sub>) cells, that were derived from T cells activated with the same antigen recognize and bind these MHC-II-peptide complexes through their TCR.<ref name=":13" /> Following TCR-MHC-II-peptide binding and the relay of other signals from the memory T<sub>FH</sub> cell, the memory B cell is activated and differentiates either into plasmablasts and plasma cells via an extrafollicular response or enter a germinal center reaction where they generate plasma cells and more memory B cells.<ref name=":13" /><ref name=":12" /> It is unclear whether the memory B cells undergo further affinity maturation within these secondary GCs.<ref name=":13" /> ''[[In vitro]]'' activation of memory B cells can be achieved through stimulation with various activators, such as pokeweed mitogen or anti-[[CD40 (protein)|CD40]] [[Monoclonal antibody|monoclonal antibodies]], however, a study found a combination of [[Resiquimod|R-848]] and [[Interleukin 2|recombinant human IL-2]] to be the most efficient activator.<ref>{{Cite journal |last1=Jahnmatz |first1=Maja |last2=Kesa |first2=Gun |last3=Netterlid |first3=Eva |last4=Buisman |first4=Anne-Marie |last5=Thorstensson |first5=Rigmor |last6=Ahlborg |first6=Niklas |date=2013-05-31 |title=Optimization of a human IgG B-cell ELISpot assay for the analysis of vaccine-induced B-cell responses |journal=Journal of Immunological Methods |language=en |volume=391 |issue=1 |pages=50–59 |doi=10.1016/j.jim.2013.02.009 |pmid=23454005 |issn=0022-1759|doi-access=free }}</ref>