Yes. Helper cells can scan MHC II complex found on antigen presenting cells or APCs. Upon recognition of abnormal antigens, they initiate a pathway that leads to plasma cell production.
Mandatory? No. Uncommon? Yes. B Cells are one of the 3 APC's (all have MHCII) and so seldomely, a B cell can activate itself but this is very difficult to achieve and not something we generally consider. Activated T helper cells facilitate the activation process in a very specific way by binding multiple receptors and other integral proteins on B cells signaling an intracellular cascade that allows for naive B cell activation and proliferation to occur.