<prompt> B lymphocytes are associated with -CD 19CD 27CD 4CD 35  <response>: Immature B cells express CD19, CD 20, CD34, CD38, and CD45R, but not IgM. For most mature B cells the key markers include IgM and CD19, a protein receptor for antigens Kaminski DA. Front Immunol. 2012. Activated B cells express CD30, a regulator of apoptosis. Plasma B cells lose CD19 expression, but gain CD78, which is used to quantify these cells. Memory B cells can be immunophenotyped using CD20 and CD40 expression. Reff: General Systemic pathology Pg: 126 