title: Detection of B-lymphocyte (B-cell)-associated antigens on human leukemic lymphocytes. Masking of membrane antigens.
abstract: An indirect immunofluorescent technic has been used for rabbit antisera (anti-EP) that demonstrated complement-dependent cytotoxicity against human leukemic lymphocytes but not against normal blood lymphocytes. With the immunofluorescent technic, the antisera were found to react with 2--23% of normal blood lymphocytes. Simultaneous staining of normal cells with anti-EP and for surface immunoglobulins (SIg) on bone-marrow-derived B-cells showed that the proportions of stained cells were similar to percentages of cells stained by anti-EP alone or for SIg alone. The percentage of anti-EP reactive cells also approximated the percentages of cells reactive to a known antiserum to human B-cell associated, or Ia-like, antigens. The anti-EP reacted with lymphoblastoid cells from two B-cell lines lacking the Epstein-Barr viral genome. The antigens detected by anti-EP probably are B-cell-associated. The anti-EP intensely stained neoplastic cells of acute or chronic lymphocytic leukemia and lymphosarcoma-cell leukemia. Cells from two patients with chronic lymphocytic leukemia and from two patients with acute lymphocytic leukemia showed increased intensity of anti-EP staining and/or increased proportions of stained cells following overnight incubation in culture medium, compared with the preincubation samples. This observation suggests the presence of a "blocking component(s)" on cell surfaces, which interfered with anti-EP reactivity. After overnight incubation, the component might have been removed from the antigenic sites on cell surfaces. Further studies of leukemia lymphocytes using anti-EP for the cell-bound "blocking component" may reveal important pathogenetic mechanisms.
mesh_terms: D000954:Antigens, Surface / Q000032:analysis*; D001402:B-Lymphocytes / Q000276:immunology; D003601:Cytotoxicity Tests, Immunologic; D005455:Fluorescent Antibody Technique; D004854:Herpesvirus 4, Human / Q000276:immunology; D006801:Humans; D007106:Immune Sera / Q000302:isolation & purification; D007938:Leukemia / Q000276:immunology*; D007945:Leukemia, Lymphoid / Q000276:immunology; D008214:Lymphocytes / Q000276:immunology*; D012397:Rosette Formation; D013601:T-Lymphocytes / Q000276:immunology
chemical_list: D000954:Antigens, Surface; D007106:Immune Sera