Editing Memory B cell (section)

== Secondary response and memory ==
The memory B cells produced during the primary immune response are specific to the antigen involved during the first exposure. In a secondary response, the memory B cells specific to the antigen or similar antigens will respond.<ref name=":02" /> When memory B cells reencounter their specific antigen, they proliferate and differentiate into plasma cells, which then respond to and clear the antigen.<ref name=":02" /> The memory B cells that do not differentiate into plasma cells at this point can reenter the germinal centers to undergo further class switching or somatic hypermutation for further affinity maturation.<ref name=":02" /> Differentiation of memory B cells into plasma cells is far faster than differentiation by naïve B cells, which allows memory B cells to produce a more efficient secondary immune response.<ref name=":3"/> The efficiency and accumulation of the memory B cell response is the foundation for vaccines and booster shots.<ref name=":3"/><ref name=":02" />

The phenotype of memory cells that prognosticate plasma cells or germinal center cells fate has been discovered  few years  ago. Based on expression microarray comparisons between memory B cells and naïve B cells, it was identified that there are several surface proteins, such as [[CD80]], PD-L2 and CD73 that are only expressed on the memory B cells, so they also serve to divide this cells in multiple phenotypic subsets.<ref>{{Cite journal|last1=Zuccarino-Catania|first1=Griselda V|last2=Sadanand|first2=Saheli|last3=Weisel|first3=Florian J|last4=Tomayko|first4=Mary M|last5=Meng|first5=Hailong|last6=Kleinstein|first6=Steven H|last7=Good-Jacobson|first7=Kim L|last8=Shlomchik|first8=Mark J|date=July 2014|title=CD80 and PD-L2 define functionally distinct memory B cell subsets that are independent of antibody isotype|journal=Nature Immunology|language=en|volume=15|issue=7|pages=631–637|doi=10.1038/ni.2914|issn=1529-2908|pmc=4105703|pmid=24880458}}</ref> Moreover, it has been shown that the memory cells that express CD80, PD-L2 and CD73 are more likely to become plasma cells. On the other hand, the cells which don´t have these type of markers are more likely to form germinal center cells. The IgM<sup>+</sup>  memory B cells do not express CD80 or CD73, whereas IgG<sup>+</sup> express them. Moreover, IgG<sup>+</sup> are more likely to differenciate into antibody-secreting cells.<ref>{{Cite journal|last1=Chong|first1=Anita S.|last2=Ansari|first2=M. Javeed|date=April 2018|title=Heterogeneity of memory B cells|journal=American Journal of Transplantation|language=en|volume=18|issue=4|pages=779–784|doi=10.1111/ajt.14669|pmc=5962275|pmid=29359404}}</ref>