It is also clearly pointed out in General Biology that when the two arms of antigen recognition receptor molecules on the surface of B cells meet the corresponding antigens and lock in the binding site, this B cell is sensitized and ready to start dividing. But it needs other suitable signals to divide, and these signals come from an activated helper T cell. Activated T cells secrete interleukin -2, which promotes the division of sensitized B cells.
It is now clear that T cells cannot transmit antigens, and the differentiation and proliferation of B cells must be lymphatic factor.