Membrane depolarization of human B cells follows stimulation by either anti-mu or B-cell growth factor, but only anti-mu causes cell volume changes.
Human peripheral blood B cells were separated from monocytes and T cells, depleted of null cells by an anti-Leu 9 rosetting technique, and fractionated on discontinuous Percoll gradients to yield a highly purified, small, dense B-cell population. These cells responded to F(ab')2 goat anti-mu at 10 and 100 micrograms/ml with membrane depolarization (measured by immunofluorescence with 3,3'-dipentyloxacarbocyanine dye) at 1 h, cell volume enlargement by 48 h, and modest thymidine incorporation by 72 h. They also responded to the 12-kd human B-cell growth factor of Maizel with membrane depolarization, but not with cell volume increase. F(ab')2 anti-mu and B-cell growth factor together induced greater depolarization than was seen with either alone, but there was no synergy. The cell volume increase seen with F(ab')2 anti-mu was not increased by B-cell growth factor. Comparison of data analysis methods showed that mean fluorescence intensity most readily detected significant depolarization. We conclude that in human B cells: (1) depolarization may be a "general response" to a variety of membrane stimuli, because F(ab')2 anti-mu and B-cell growth factor acting through different receptors both induce it, and (2) depolarization does not inevitably lead to cell volume increase.
D000937:Antigen-Antibody Reactions; D001402:B-Lymphocytes / Q000276:immunology*; D002232:Carbocyanines; D002469:Cell Separation; D005434:Flow Cytometry; D005456:Fluorescent Dyes; D006801:Humans; D007148:Immunoglobulin mu-Chains / Q000276:immunology*; D066298:In Vitro Techniques; D015847:Interleukin-4; D007378:Interleukins / Q000276:immunology*; D008213:Lymphocyte Activation; D008564:Membrane Potentials
D002232:Carbocyanines; D005456:Fluorescent Dyes; D007148:Immunoglobulin mu-Chains; D007378:Interleukins; D015847:Interleukin-4; C018528:3,3'-dipentyl-2,2'-oxacarbocyanine