Division and differentiation of B cells leading to production of plasma cells both require:

Amplification of pre B cells along the pathway leading to the terminal plasma cell requires interleukin (IL)-4 and IL-6. IL-1 is involved mainly in T-cell activation. CD4 and CD8 function during interaction of the T cell with antigen-presenting cells. Ref: Harrison's Principles of Internal Medicine, 17th Edition, Chapter 308, Page 2025, Table 308-6