title: Human tonsil B lymphocyte function. II. Pokeweed mitogen-induced plasma cell differentiation of B cell subpopulations expressing multiple heavy chain isotypes on their surface.
abstract: Human tonsil non-T cells were successfully separated into surface IgM+G-ve (sIgM+G-), sIgM+G+, sIgM-G-, and sIgM-G+ B cell fractions. The two-step separation technique used did not affect the pokeweed mitogen- (PWM) induced plasma cell differentiation of the B cells. The highest percentages of plasma cells after PWM stimulation were found in the sIgM- fractions, and the lowest percentage was in the sIgM+G- fraction (20.8 +/- 2.3%), the latter predominantly cytoplasmic mu-chain-positive (c mu +) (84.1 +/- 3.5%) plasma cells. In this fraction, almost no c gamma + plasma cells were found. The sIgM+G+ produced c mu + (47.5 +/- 7.5%), c gamma + (35.7 +/- 5.8%), and c alpha + (16.8 +/- 4.0%) plasma cells. All three isotypes were found on the surface of the B cells in this fraction before PWM stimulation. The sIgM-G- fraction contained about 10% plasma cells before stimulation, which were predominantly c gamma +. After PWM stimulation, primarily c alpha + (64.2 +/- 4.3%) plasma cells were found. The sIgM-G+ fraction produced both c gamma + (75.0 +/- 2.3%) and c alpha + (24.1 +/- 2.5) plasma cells. A mu to gamma class switch did not occur in vitro in the sIgM+G- fraction on PWM stimulation, and the sIgM+G+ fraction did not complete in vitro the mu to gamma switch it had started in vivo.
mesh_terms: D001402:B-Lymphocytes / Q000145:classification* / Q000166:cytology / Q000276:immunology; D002454:Cell Differentiation; D002469:Cell Separation; D002648:Child; D006801:Humans; D007126:Immunoglobulin Allotypes / Q000032:analysis*; D007074:Immunoglobulin G / Q000032:analysis; D007075:Immunoglobulin M / Q000032:analysis; D014066:Palatine Tonsil / Q000166:cytology*; D010950:Plasma Cells / Q000166:cytology*; D011043:Pokeweed Mitogens / Q000494:pharmacology; D011947:Receptors, Antigen, B-Cell / Q000032:analysis*; D012397:Rosette Formation; D013601:T-Lymphocytes
chemical_list: D007126:Immunoglobulin Allotypes; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D011043:Pokeweed Mitogens; D011947:Receptors, Antigen, B-Cell