Figure 2.

B cells in graft-versus-leukaemia responses.

B cells can exert antitumour effects via a number of mechanisms. (1) Antibodies secreted by plasma cells can induce antibody-dependent cellular cytotoxicity, antibody-dependent cellular phagocytosis, complement-dependent cytotoxicity or can be directly cytotoxic. (2) B cells can act as antigen-presenting cells when cognate antigens bound to membrane-expressed immunoglobulin are internalized, processed and presented in the context of major histocompatibility complex (MHC) to T cells. (3) B cells can modulate the tumour microenvironment and antitumour immune responses via the secretion of pro-inflammatory cytokines, such as interleukin (IL)-2, tumour necrosis factor-α, IL-6, IL-12, migration inhibitory factor and interferon-γ. (4) B cells can produce cytotoxic granzyme B (GZB); Mϕ, macrophage.