(Science: haematology, immunology) a type of lymphocyte normally involved in the production of antibodies to combat infection. It is a precursor to a plasma cell. During infections, individual b-cell clones multiply and are transformed into plasma cells, which produce large amounts of antibodies against a particular antigen on a foreign microbe. This transformation occurs through interaction with the appropriate cd4 t helper cells. Lymphocytes that are capable of producing antibodies in response to detecting the presence of a particular [[antigen.