B cell activation can occur through two primary pathways: T cell-dependent and T cell-independent. In the T cell-dependent pathway, B cells internalize the antigen, process it, and present it on MHC class II molecules to helper T cells. The interaction with helper T cells provides additional signals through cytokines and CD40/CD40L interactions, leading to B cell proliferation and differentiation. In the T cell-independent pathway, B cells can be directly activated by certain antigens, such as polysaccharides, without the need for T cell help.
