The Role Of P38 MAPK In Plasma Cell Differentiation

Plasma cells differentiated from naive B cells is the most important event in humoral immune responses.In a T-cell dependent antibody response,naive B cells firstly differentiated to germinal center B cells,which immediately differentiated to plasma cells under IL-21 stimulation.Until now,mechanisms of this progress are still unclear.In this study,we use an in vitro plasma cell differentiation culture system to study the role of p38a MAPK in plasma cell differentiation.Our results clearly show that p38a is not involved in germinal center B cells differentiation,but it plays an indispensable role in plasma cell differentiation.More importantly,p38a is also necessary for plasma cells endoplasmic reticulum expansion and antibody secretion.The kinase activity and the T180/Y182 phosphorylation of p38a are necessary for these progresses.We find Blimp 1,the master regulator of plasma cell differentiation,is significant down-regulated in p38a knockout B cells,and over-express Blimp 1 in p38a knockout B cells can rescue differentiation defect in p38a knockout cells.Besides,p38?deficiency have no effect on plasma cell differentiation.Our results suggest an important role of p38a in humoral immune responses and need further investigation.