Dendritic cells, B cells and the regulation of antibody synthesis.

Dendritic cells (DC) are usually thought of as antigen-presenting cells for T cells. However, recent studies from our laboratory and those of others have shown that they have important roles in B-cell activation and regulation of antibody synthesis. Rat DC make short term interactions with resting B cells and these interactions can be stimulated by cross-linking molecules on either cell surface. These DC can retain antigen in native form for at least 36 h in vivo and in vitro and can subsequently release it for recognition by B cells. In vivo antibody responses induced by antigen-pulsed DC are skewed towards IgG. In vitro, naäive B cells incubated with antigen-pulsed DC subsequently secrete IgM and IgG when cultured with an antigen-specific CD4+ T-cell line, whereas if B cells are incubated with antigen without DC, only IgM is produced. These observations show that DC play an important role in the initiation of and regulation of antibody synthesis.