The role of B lymphocytes as antigen-presenting cells.
B lymphocytes are regarded as professional antigen-presenting cells (APCs) despite their primary role in humoral immunity. Over the last two decades, studies designed to define the role of the B cells as APCs have generated discrepant results, showing that B cells are either unnecessary or required for T cell priming and either immunogenic or tolerogenic to T cells. The reasons for these discrepancies are not clear. Here we review mechanisms regulating B cell antigen presentation and the data derived from the major studies conducted by different groups representing each school of thought. In general it is clear that B cells process and present specific and nonspecific antigens differently. The presentation of specific antigen through the B cell antigen receptor occurs with very high efficiency and is associated with B cell activation, resulting in the activation of cognate T cells. In contrast, the presentation of nonspecific antigen by B cells is minimized and dissociated from B cell activation. As a result, B cells inactivate T cells that recognize nonspecific antigenic epitopes presented by B cells, or they induce regulatory T cell differentiation or expansion. These mechanisms serve to ensure effective production of high-affinity antigen-specific antibodies but minimize the production of nonspecific antibodies and autoantibodies.
Chen
Xinjian
X
Department of Pathology, University of Utah, Emma Eccles Jones, Medical Research Building, 15 North Medical Drive East, Ste 1100, Salt Lake City, Utah, 84112-5650, USA.
Jensen
Peter E
PE
D000818:Animals; D017951:Antigen Presentation; D000938:Antigen-Presenting Cells / Q000502:physiology*; D001402:B-Lymphocytes / Q000502:physiology*; D000949:Histocompatibility Antigens Class II / Q000502:physiology; D006801:Humans; D008213:Lymphocyte Activation
D000949:Histocompatibility Antigens Class II