The antigen processing pathway in B lymphocytes.

Monovalent antigen bound to membrane immunoglobulin on human B lymphoblastoid cells is endocytosed through coated pits and passes sequentially from a site which actively recycles membrane to the cell surface and then to a proteolytically active processing site. A high affinity of immunoglobulin for antigen precludes antigen dissociation following endocytosis and results in the processing of an antigen/Ig complex yielding an epitope-specific pattern of processing. Processing of the immunoglobulin also occurs and is enhanced by occupancy with monovalent antigen.