title: Loss of CD19 expression in B-cell neoplasms.
abstract: OBJECTIVE
  To investigate whether an antibody against an intracellular epitope can detect CD19 in routine biopsy specimens and thus to document in detail its expression in human lymphomas.
  
  
  RESULTS
  A polyclonal antibody to the C terminus of CD19 was used to immunostain paraffin-embedded samples of normal and neoplastic lymphoid tissues. CD19 was widely expressed in normal B cells and in extramedullary plasma cells. It was found in most B-cell neoplasms, but expression in follicular lymphoma was weak (33/69) or negative (four cases). Similarly, CD19 expression in diffuse large B-cell lymphomas was weak (28/56) or negative (eight cases). In T-cell-rich B-cell lymphomas, CD19 was also weak (4/10) or negative (three cases). CD19 was often absent in post-transplant B lymphoproliferative disease, classical Hodgkin's disease and plasma cell neoplasms. An unexpected finding was the frequent absence of CD19 in the neoplastic cells in lymphocyte predominant Hodgkin's disease.
  
  
  CONCLUSIONS
  CD19 can now be detected in routine biopsy specimens. In contrast to the classical pan-B marker CD20, CD19 is not always strongly expressed in B-cell neoplasms. Furthermore, the lymphocytic and histiocytic (L&H) cells of lymphocyte predominant Hodgkin's disease (which express most B-cell-associated markers) commonly lack CD19.
authors.affiliation: Leukaemia Research Fund Immunodiagnostics Unit, Nuffield Department of Clinical Laboratory Sciences, University of Oxford, John Radcliffe Hospital, Oxford, UK.
authors.forename: N
authors.initials: N
authors.lastname: Masir
authors.forename: T
authors.initials: T
authors.lastname: Marafioti
authors.forename: M
authors.initials: M
authors.lastname: Jones
authors.forename: Y
authors.initials: Y
authors.lastname: Natkunam
authors.forename: T
authors.initials: T
authors.lastname: Rüdiger
authors.forename: M-L
authors.initials: ML
authors.lastname: Hansmann
authors.forename: D Y
authors.initials: DY
authors.lastname: Mason
mesh_terms: D018941:Antigens, CD19 / Q000096:biosynthesis* / Q000235:genetics; D001402:B-Lymphocytes / Q000378:metabolism / Q000473:pathology; D005455:Fluorescent Antibody Technique; D015972:Gene Expression Regulation, Neoplastic; D006689:Hodgkin Disease / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology; D006801:Humans; D007150:Immunohistochemistry; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology; D016393:Lymphoma, B-Cell / Q000235:genetics* / Q000378:metabolism / Q000503:physiopathology; D016403:Lymphoma, Large B-Cell, Diffuse / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology; D016399:Lymphoma, T-Cell / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology; D010950:Plasma Cells / Q000378:metabolism / Q000473:pathology
chemical_list: D018941:Antigens, CD19