B cell activation. II. Receptor cross-linking by thymus-independent and thymus-dependent antigens induces a rapid decrease in the plasma membrane potential of antigen-binding B lymphocytes.
We report the specific induction of B cell plasma membrane depolarization with the use of thymus-dependent and -independent antigens. We have utilized various trinitrophenol-carrier conjugates for the stimulation of isolated trinitrophenol-binding mouse B cells. Membrane depolarization was assessed by flow cytometric analysis of 3-3'-pentyloxacarbocyanine iodide (DiOC5[3])-stained cells. Entry into the cell cycle was determined by flow cytometric analysis of acridine orange-stained cells. The results indicate that polyvalent antigens, but not free hapten, induce B cell membrane depolarization by a large proportion of antigen-binding cells within 2 hr of stimulation. Although all polyvalent antigens induce membrane depolarization, only thymus-independent antigens induce the subsequent G0 to G1 transition, suggesting that the membrane Ig cross-linking signal alone, although sufficient to induce membrane depolarization and subsequent increased IA expression, is insufficient to drive the entry of B cells into the cell cycle. The G0 to G1 transition appears to be dependent on a second signal, perhaps mediated by the thymus-independent carrier or antigen-specific, Ia-restricted T cell helper.
D000818:Animals; D000955:Antigens, T-Independent / Q000276:immunology*; D001402:B-Lymphocytes / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D002453:Cell Cycle; D002462:Cell Membrane / Q000378:metabolism; D000939:Epitopes; D006241:Haptens / Q000276:immunology; D008213:Lymphocyte Activation; D008564:Membrane Potentials; D051379:Mice; D008815:Mice, Inbred Strains; D011947:Receptors, Antigen, B-Cell / Q000378:metabolism*
D000955:Antigens, T-Independent; D000939:Epitopes; D006241:Haptens; D011947:Receptors, Antigen, B-Cell