Transfer of antigen from human B cells to dendritic cells

•B cells act as antigen presenting cells in T cell activation.•Human B lymphocytes transfer antigen to dendritic cells.•Scavenger receptor A mediates antigen transfer from B cells to dendritic cells.•Scavenger receptor A may represent a therapeutic target in autoimmune disease.

The cooperation of B lymphocytes with other antigen presenting cells (APCs) is often necessary in the efficient processing and presentation of antigen. Herein, we describe a mechanism by which B cells physically interact with dendritic cells (DCs) resulting in the transfer of B cell receptor (BCR)-enriched antigen to these APCs. Antigen transfer involves direct contact between the two cells followed by the capture of B cell derived membrane and intracellular components. Strikingly, DCs acquire greater amounts of antigen by transfer from B cells than by endocytosis of free antigen. Blocking scavenger receptor A, a DC surface receptor involved in membrane acquisition, abrogates these events. We propose that antigen transfer from B cells to DCs results in a more focused immunologic response due to the selective editing of Ag by the BCR.